Oxygen absorption resin composition

ABSTRACT

An oxygen absorption resin composition is provided that comprises a thermoplastic resin (A) having carbon-carbon double bonds substantially in its main chain and a transition metal salt (B). If necessary, the composition further comprises a gas barrier resin (C), a compatibilizer (D) and the like. The composition has excellent oxygen absorption properties, and when the composition is employed, generation of odorous substances derived from the decomposition of resins as a result of oxygen absorption can be suppressed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an oxygen absorption resin compositionthat has excellent oxygen absorbency and does not emit unpleasant odoras a result of oxygen absorption.

2. Description of the Related Art

Gas barrier resins such as ethylene-vinyl alcohol copolymer (hereinafteralso abbreviated as EVOH) are materials having excellent oxygen gasbarrier properties and carbon dioxide gas barrier properties. Such aresin can be melt-molded and therefore is used preferably for amultilayered plastic packaging material comprising a layer of the resinlaminated with a layer made of a thermoplastic resin (e.g., polyolefin,polyester, etc.) having excellent moisture-resistance, mechanicalproperties, and the like. However, the gas transmission of these gasbarrier resins is not completely zero, and they transmit an amount ofgas that cannot be ignored. It is known to use an oxygen absorbent inorder to reduce transmission of such a gas, in particular, oxygen, whichaffects the quality of the content significantly, or in order to removeoxygen that already is present inside a packaging member at the time ofpackaging its content.

For example, as an improved oxygen absorbent, a composition comprising atransition metal catalyst and an ethylenically unsaturated compound (seeJapanese Laid-Open Patent Publication No. 5-115776) and an oxygenscavenger that is a cross-linked polymer (see Japanese Laid-Open PatentPublication No. 11-70331) have been proposed. Furthermore, a resincomposition containing EVOH as described above and an oxygen absorbenthas been proposed (Japanese Laid-Open Patent Publication Nos.2001-106866, 2001-106920 and 2002-146217). In particular, similarly toEVOH, the resin composition containing EVOH can be melt-molded andtherefore can be used preferably for various packaging materials.

However, when the oxygen absorbent or the oxygen absorption resincomposition as described above is used as a packaging material, theoxygen absorbent is decomposed as the oxygen absorption proceeds, and aunpleasant odor may be emitted. Furthermore, the mold-processability ofthe cross-linked polymers is poor, and therefore, when the polymers arekneaded with a thermoplastic resin, gels are produced, resulting in poormolding, and thus they cannot be put to practical use. In this way,there has been a demand for further improvement in applications in whichfragrance is important.

SUMMARY OF THE INVENTION

An oxygen absorption resin composition of the present inventioncomprises a thermoplastic resin (A) having carbon-carbon double bondssubstantially in its main chain and a transition metal salt (B).

In a preferred embodiment, the following inequality (1) is satisfied inthe thermoplastic resin (A):100×b/(a+b)≦7  (1)wherein a (mol/g) is an amount of the carbon-carbon double bonds in itsmain chain, and b (mol/g) is an amount of the carbon-carbon double bondsin its side chain.

In a preferred embodiment, the thermoplastic resin (A) comprises atleast one of the units represented by formula (I) and formula (II):

wherein R₁, R₂, R₃ and R₄ are the same or different, a hydrogen atom, analkyl group that may be substituted, an aryl group that may besubstituted, an alkylaryl group that may be substituted, —COOR₅, —OCOR₆,a cyano group or a halogen atom, and R₃ and R₄ may together form a ringvia a methylene group or an oxymethylene group, where R₅ and R₆ are analkyl group that may be substituted, an aryl group that may besubstituted or an alkylaryl group that may be substituted.

In a preferred embodiment, R₁, R₂, R₃ and R₄ are hydrogen atoms in theformula (I) and formula (II).

In a preferred embodiment, the thermoplastic resin (A) is at least oneresin selected from the group consisting of polybutadiene, polyisoprene,polychloroprene, and polyoctenylene.

In a preferred embodiment, the thermoplastic resin (A) is at least oneresin selected from the group consisting of polybutadiene andpolyoctenylene.

In a preferred embodiment, the transition metal salt (B) is at least onemetal salt selected from the group consisting of an iron salt, a nickelsalt, a copper salt, a manganese salt and a cobalt salt.

In a preferred embodiment, the oxygen absorption rate of the resincomposition is at least 0.01 ml/(g-day).

In a preferred embodiment, the resin composition further comprises a gasbarrier resin (C) having an oxygen transmission rate of 500 ml·20μm/(m²·day·atm) or less in 65% RH at 20° C.

In a preferred embodiment, the gas barrier resin (C) is at least oneresin selected from the group consisting of a polyvinyl alcohol resin, apolyamide resin, a polyvinyl chloride resin and a polyacrylonitrileresin.

In a preferred embodiment, the gas barrier resin (C) is anethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60mol % and a saponification degree of 90% or more.

In a preferred embodiment, the gas barrier resin (C) is contained in anamount of 70 to 99 wt % and the thermoplastic resin (A) is contained inan amount of 30 to 1 wt %, when the total weight of the thermoplasticresin (A) and the gas barrier resin (C) is determined to be 100 wt %.

In a preferred embodiment, the resin composition further comprises acompatibilizer (D).

In a preferred embodiment, the gas barrier resin (C) is contained in anamount of 70 to 98.9 wt %, the thermoplastic resin (A) is contained inan amount of 29.9 to 1 wt %, and the compatibilizer (D) is contained inan amount of 29 to 0.1 wt %, when the total weight of the thermoplasticresin (A), the gas barrier resin (C) and the compatibilizer (D) isdetermined to be 100 wt %.

In a preferred embodiment, particles of the thermoplastic resin (A) aredispersed in a matrix of the gas barrier resin (C) in the composition.

The present invention further includes a molded product that comprisesthe oxygen absorption resin composition; a multilayered structure and amultilayered container, both of which comprises a layer made of theresin composition; a multilayered container made of a multilayered filmhaving a total layer thickness of 300 μm or less, wherein themultilayered film comprises a layer made of the resin composition; amultilayered container comprising a layer made of the resin compositionand a thermoplastic polyester layer; and a cap having a cap body that isprovided with a gasket made of the resin composition.

Thus, the invention described herein makes possible the advantages of:providing an oxygen absorption resin composition that has excellentoxygen absorbency and does not generate unpleasant odor by oxygenabsorption; providing a molded product comprising a resin compositionhaving the above-described excellent properties, for example, amultilayered film or a multilayered container including layers made ofthe resin composition; providing a container comprising the resincomposition having the above-described excellent properties that issuitable to store articles such as foods, cosmetics or the like that aresusceptible to deterioration caused by oxygen and for which fragrance isimportant; and providing a resin composition having high oxygenscavenging function, and thus useful as an oxygen scavenger that can behandled easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph in which the oxygen absorption amount of each of thesheets obtained in Examples 1.1 and 1.2 and Comparative Example 1 isplotted against time.

FIG. 2 is a graph in which the oxygen absorption amount of each of thesheets obtained in Examples 2.1 to 2.5 and Comparative Example 2 in a100% RH atmosphere at 60° C. is plotted against time.

FIG. 3 is a graph in which the oxygen absorption amount of each of thesheets obtained in Examples 2.1 to 2.5 and Comparative Example 2 in a100% RH atmosphere at 23° C. is plotted against time.

FIG. 4 is a graph in which the oxygen absorption amount of each of thefilms obtained in Examples 3.1 to 3.4 and Comparative Examples 3.1 and3.2 in a 100% RH atmosphere at 60° C. is plotted against time.

FIG. 5 is a graph in which the oxygen absorption amount of each of thefilms obtained in Examples 3.1 to 3.4 and Comparative Examples 3.1 and3.2 in a 100% RH atmosphere at 23° C. is plotted against time.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In this specification, “scavenging oxygen” means absorbing and consumingoxygen or reducing the amount of oxygen from a given environment.

An oxygen absorption resin composition of the present inventioncomprises a thermoplastic resin (A) having carbon-carbon double bondssubstantially in its main chain and a transition metal salt (B), and, ifnecessary, a gas barrier resin (C), a compatibilizer (D) and anotherthermoplastic resin (E), and various additives. These components will bedescribed in this order below.

(1) Thermoplastic Resin (A) Having Carbon-Carbon Double BondsSubstantially in its Main Chain

The resin composition of the present invention comprises a thermoplasticresin (A) having carbon-carbon double bonds substantially in its mainchain (in this specification, this resin is also referred to as“thermoplastic resin (A)” or “resin (A)”). Herein, “the thermoplasticresin (A) has carbon-carbon double bonds substantially in its mainchain” means that the carbon-carbon double bonds present in the mainchain of the resin (A) account for 90% or more, and the carbon-carbondouble bonds present in the side chains of the resin (A) account for 10%or less of all the carbon-carbon double bonds in the molecule of theresin (A). The carbon-carbon double bonds present in the side chainspreferably account for 7% or less, and more preferably 5% or less. Morespecifically, in the resin (A), the following inequality (1) issatisfied:100×b/(a+b)≦X  (1)

-   -   wherein a (mol/g) is an amount of the carbon-carbon double bonds        in the main chain, and b (mol/g) is an amount of the        carbon-carbon double bonds in the side chains, and wherein X is        10, preferably 7, and more preferably 5.

Since the thermoplastic resin (A) has carbon-carbon double bonds withinits molecule, the thermoplastic resin (A) can react with oxygenefficiently, and therefore the oxygen scavenging function (i.e., oxygenabsorption function) can be obtained. The carbon-carbon double bonds asused herein include conjugated double bonds, but do not include multiplebonds contained in an aromatic ring. The amount of the carbon-carbondouble bonds contained in the thermoplastic resin (A) is preferably0.001 eq/g (equivalents/g) or more, more preferably 0.005 eq/g or more,and even more preferably 0.01 eq/g or more. When the content of thecarbon-carbon double bonds is less than 0.001 eq/g, the oxygenscavenging function of the resultant resin composition may beinsufficient.

As described above, since the thermoplastic resin (A) has carbon-carbondouble bonds substantially in its main chain, low molecular weightdegradation products formed by the cleavage of the double bonds in itsside chains due to a reaction with oxygen are substantially not formed.Some of the low molecular weight degradation product may emit unpleasantodor, and since such degradation products are not formed, there is nounpleasant odor. On the other hand, when a thermoplastic resin havingcarbon-carbon double bonds in its side chains is employed, degradationproducts are produced by the cleavage of the double bonds in the sidechains, as described above, although there is no problem in terms ofoxygen absorption. Therefore, unpleasant odor is emitted, and may impairthe ambient atmosphere significantly.

In the thermoplastic resin (A), when a carbon-carbon double bond in themain chain is reacted with oxygen, oxidation is effected at an allylcarbon (i.e., carbon adjacent to the double bond) site, so that it ispreferable that the allyl carbon is not a quaternary carbon.Furthermore, it is still possible that a low molecular weightdegradation product may be formed by the cleavage of the main chain, sothat in order to suppress this, it is preferable that the allyl carbonis a non-substituted carbon, that is, a methylene carbon. Accordingly,it is preferable that the thermoplastic resin (A) has at least one ofthe units represented by formula (I) and formula (II):

-   -   wherein R₁, R₂, R₃ and R₄ are the same or different, a hydrogen        atom, an alkyl group that may be substituted, an aryl group that        may be substituted, an alkylaryl group that may be substituted,        —COOR₅, —OCOR₆, a cyano group or a halogen atom, and R₃ and R₄        may together form a ring via a methylene group or an        oxymethylene group, where R₅ and R₆ are an alkyl group that may        be substituted, an aryl group that may be substituted or an        alkylaryl group that may be substituted.

The number of carbon atoms of the alkyl group is preferably 1 to 5. Thenumber of carbon atoms of the aryl group is preferably 6 to 10. Thenumber of carbon atoms of the alkylaryl group is preferably 7 to 11.Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, and a butyl group. An example of the aryl group includes aphenyl group. An example of the alkylaryl group includes a tolyl group.An example of the halogen atom includes a chlorine atom. Furthermore,examples of the substituent that can be present in the thermoplasticresin (A) include various hydrophilic groups. “Hydrophilic group” hereinrefers to a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms,an amino group, an aldehyde group, a carboxyl group, an epoxy group, anester group, a carboxylic acid anhydride group, and a polar groupcontaining boron (e.g., a boronic acid group, a boronic ester group, aboronic acid anhydride group and a boronate group).

Among the above thermoplastic resins (A), compounds in which all R₁, R₂,R₃ and R₄ are hydrogen atoms in each unit of the formulae (I) and (II)constituting the resin are particularly preferable in terms ofpreventing odor. The reason for this is not fully clear, but it istheorized that when R₁, R₂, R₃ and R₄ are groups other than hydrogen,these groups may be oxidized and cleaved, and thus changed into anodorous substance when the thermoplastic resin (A) is reacted withoxygen.

Among the units represented by formulae (I) and (II), a unit derivedfrom a diene compound is preferable. This is because the thermoplasticresin having that structure can be easily produced. Examples of such adiene compound include isoprene, butadiene, 2-ethylbutadiene, and2-butylbutadiene, and chloroprene. One of these can be used, or two ormore can be used in combination. Examples of the thermoplastic resin (A)containing these units include polybutadiene, polyisoprene,polychloroprene and polyoctenylene. Among these, polybutadiene orpolyoctenylene is particularly preferable. As the thermoplastic resin(A), a copolymer containing the above-described unit and another unitthan that can be used. As a copolymerized component, styrene,acrylonitrile, or propylene can be employed. When the thermoplasticresin (A) is such a copolymer, the total content of the unit shown bythe formula (I) and the unit shown by the formula (II) is preferably 50mol % or more, and more preferably 70 mol % or more with respect to allthe units constituting the copolymer.

The number average molecular weight of the thermoplastic resin (A) ispreferably 1000 to 500000, more preferably 5000 to 300000, even morepreferably 10000 to 250000, and particularly preferably 40000 to 200000.When the molecular weight of the thermoplastic resin (A) is less than1000 or more than 500000, the mold-processability and the handlingproperties of the resultant resin composition may be poor, or themechanical properties such as strength or elongation may be decreasedwhen the resin is formed into a molded product. Furthermore, when thethermoplastic resin (A) is mixed with a gas barrier resin (C), whichwill be described later, then the dispersion may be lowered, andconsequently the gas barrier properties and the oxygen scavengingperformance may be degraded.

The thermoplastic resin (A) can be a single resin or a mixture of aplurality of resins.

A method for producing the thermoplastic resin (A) having carbon-carbondouble bonds substantially in its main chain is not limited and maydepend on the kind of the thermoplastic resin (A). For example, in thecase of polybutadiene (e.g., cis-1,4-polybutadiene), the thermoplasticresin (A) can be synthesized using a cobalt-based or nickel-basedcatalyst as the catalyst. More specifically, for example, a combinationof a CoCl₂.2C₅H₅N complex and diethyl aluminum chloride can be used assuch a catalyst. An example of a solvent that can be used is an inactiveorganic solvent. Above all, hydrocarbons having 6 to 12 carbon atoms,for example, alicyclic hydrocarbons such as hexane, heptane, octane, anddecane, or aromatic hydrocarbons such as toluene, benzene, and xyleneare preferable. The polymerization is generally carried out at atemperature of −78 to 70° C. for 1 to 50 hours.

The carbon-carbon double bonds present after polymerization can bepartly reduced with hydrogen within the range not interfering with theeffects of the resin composition of the present invention. In this case,it is preferable that the carbon-carbon double bonds that remain in theside chains are selectively reduced with hydrogen.

The thermoplastic resin (A) can contain an antioxidant. As theantioxidant, for example, the following compounds can be used:2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol,4,4,′-thiobis(6-tert-butylphenol),2,2′-methylene-bis(4-methyl-6-tert-butylphenol),octadecyl-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate,4,4′-thiobis(6-tert-butylphenol),2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate,pentaerythritoltetrakis(3-laurylthiopropionate),2,6-di-(tert-butyl)-4-methylphenol (BHT),2,2-methylenebis(6-tert-butyl-p-cresol), triphenyl phosphite,tris(nonylphenyl) phosphite, dilauryl thiodipropionate or the like.

The amount of the antioxidant to be contained in the thermoplastic resin(A) is determined as appropriate, in view of the kinds and the contentsof components of the resin composition, and the use and the storageconditions of the resin composition, and the like. In general, theamount of the antioxidant is preferably 0.01 to 1% by weight, morepreferably 0.02 to 0.5% by weight, based on the total weight of thethermoplastic resin (A) and the antioxidant. If the amount of theantioxidant is too large, the reaction of the thermoplastic resin (A)and oxygen is inhibited, so that the oxygen scavenging function of theresin composition of the present invention may be insufficient. On theother hand, if the amount of the antioxidant is too small, the reactionwith oxygen may proceed during storage or melt-kneading of thethermoplastic resin (A), so that the oxygen scavenging function may belowered before the resin composition of the present invention isactually put to use.

For example, in the case where the thermoplastic resin (A) is stored ata comparatively low temperature or under an inactive gas atmosphere, orin the case where the resin composition is produced by melt-kneading insealing with nitrogen, the amount of the antioxidant can be small. Inthe case where an oxidation catalyst is added in a comparatively largeamount to facilitate oxidation, even though the thermoplastic resin (A)contains a certain amount of an antioxidant, a resin composition havinggood oxygen scavenging function can be obtained.

(2) Transition Metal Salt (B)

The transition metal salt (B) has an effect of improving the oxygenscavenging function of the resin composition by facilitating theoxidation reaction of the thermoplastic resin (A). For example, thetransition metal salt (B) facilitates a reaction of the thermoplasticresin (A) and oxygen present inside a packaging material obtained fromthe resin composition of the present invention as well as a reaction ofthe thermoplastic resin (A) and oxygen that is passing through thepackaging material, so that the oxygen scavenging function of thepackaging material can be improved.

Examples of the transition metal contained in the transition metal salt(B) include, but are not limited to, iron, nickel, copper, manganese,cobalt, rhodium, titanium, chromium, vanadium, and ruthenium. Amongthese metals, iron, nickel, copper, manganese, and cobalt arepreferable, manganese and cobalt are more preferable, and cobalt is evenmore preferable.

Examples of counter ions for the metal contained in the transition metalsalt (B) include an anion derived from an organic acid or a chloride.Examples of the organic acid include, but are not limited to, aceticacid, stearic acid, acetylacetone, dimethyldithiocarbamic acid, palmiticacid, 2-ethylhexanoic acid, neodecanoic acid, linoleic acid, tallicacid, oleic acid, resin acid, capric acid, and naphthenic acid.Especially preferred salts are cobalt 2-ethylhexanoate, cobaltneodecanoate, and cobalt stearate. The metal salt may be a so-calledionomer having a polymeric counter ion.

The transition metal salt (B) is contained in the composition preferablyin a ratio of 1 to 50000 ppm in terms of the metal element with respectto the weight of the thermoplastic resin (A). The transition metal salt(B) is contained more preferably in a ratio of 5 to 10000 ppm, and evenmore preferably in a ratio of 10 to 5000 ppm. When the resin compositionof the present invention contains a gas barrier resin (C), in additionto the thermoplastic resin (A), as described later, the transition metalsalt (B) is contained preferably in a ratio of 1 to 50000 ppm in termsof the metal element with respect to the total amount of thethermoplastic resin (A) and the gas barrier resin (C). When the resincomposition contains a gas barrier resin (C) and a compatibilizer (D),in addition to the thermoplastic resin (A), as described later, thetransition metal salt (B) is contained preferably in a ratio of 1 to50000 ppm in terms of the metal element with respect to the total amountof the thermoplastic resin (A), the gas barrier resin (C) and thecompatibilizer (D). In each of the cases, more preferably, thetransition metal salt (B) is contained preferably in a ratio of 5 to10000 ppm, and even more preferably in a ratio of 10 to 5000 ppm. If thecontent of the transition metal salt (B) is less than 1 ppm, the oxygenabsorption effect of the resin composition may be insufficient. On theother hand, if the content of the transition metal salt (B) is more than50000 ppm, the thermal stability of the resin composition may bedegraded, and a significant amount of decomposed gas, gels or aggregatesmay be generated.

(3) Gas Barrier Resin (C)

As the gas barrier resin (C) that can be contained in the oxygenabsorption resin composition of the present invention, a gas barrierresin (C) having an oxygen transmission rate of 500 ml·201m/(m²·day·atm) or less in 65% RH at 20° C. is preferable. This meansthat the volume of oxygen that is to be transmitted through a filmhaving an area of 1 m² and a thickness of 20 μm per day under adifferential pressure of oxygen of 1 atm is 500 ml or less whenmeasurement is performed in a relative humidity of 65% at a temperatureof 20° C. If a resin having an oxygen transmission rate of more than 500ml·20 μm/(m²·day·atm) is employed, the gas barrier properties of theresultant resin composition may be insufficient. The oxygen transmissionrate of the gas barrier resin (C) is preferably 100 ml·20μm/(m²·day·atm) or less, more preferably 20 ml·20 μm/(m²·day·atm) orless, and most preferably 5 ml·20 μm/(m²·day·atm) or less. Such a gasbarrier resin (C) and the thermoplastic resin (A) having carbon-carbondouble bonds are contained, so that the oxygen absorption effect as wellas the gas barrier properties are exhibited, and consequently a resincomposition having exceptionally high gas barrier properties can beobtained.

Typical examples of the above-described gas barrier resin (C) include apolyvinyl alcohol resin (C1), a polyamide resin (C2), a polyvinylchloride resin (C3) and a polyacrylonitrile resin (C4), but are notlimited thereto.

Of the gas barrier resin (C), the polyvinyl alcohol resin (C1) isobtained by saponifying a vinyl ester homopolymer or a copolymer ofvinyl ester and another monomer (especially, a copolymer of vinyl esterand ethylene) using an alkaline catalyst or the like. A typical compoundas the vinylester can be vinyl acetate, but other fatty acid vinylesters(e.g., vinyl propionate, vinyl pivalate, etc.) also can be used.

The degree of saponification of the vinyl ester component of thepolyvinyl alcohol resin is preferably 90% or more, more preferably 95%or more, even more preferably 96% or more. If the degree ofsaponification is less than 90%, the gas barrier properties under highhumidity may be lowered. Further, when the polyvinyl alcohol resin is anethylene-vinyl alcohol copolymer (EVOH), the thermal stability isinsufficient, and the resultant molded product tends to contain gels oraggregates.

When the polyvinyl alcohol resin is a blend of at least two kinds ofpolyvinyl alcohol resins having different degrees of saponification, theaverage calculated based on the blend weight ratio is determined as thedegree of saponification of the blend.

Among the polyvinyl alcohol resins as described above, EVOH ispreferable because melt-molding is possible and its gas barrierproperties under high humidity are good.

The ethylene content of EVOH is preferably in the range of 5 to 60 mol%. If the ethylene content is less than 5 mol %, the gas barrierproperties under high humidity may be low and the melt moldability maybe poor. The ethylene content of EVOH is preferably 10 mol % or more,more preferably 15 mol % or more, most preferably 20 mol % or more. Ifthe ethylene content exceeds 60 mol %, sufficiently good gas barrierproperties may not be obtained. The ethylene content is preferably 55mol % or less, more preferably 50 mol % or less.

The EVOH to be used preferably has an ethylene content of 5 to 60 mol %and a degree of saponification of 90% or more, as described above. Whenthe multilayered container comprising the resin composition of thepresent invention is desired to have an excellent impact delaminationresistance, it is preferable to employ an EVOH having an ethylenecontent of 25 mol % or more and 55 mol % or less and a degree ofsaponification of 90% or more and less than 99%.

When the EVOH is a blend of at least two kinds of EVOH having differentethylene contents, the average calculated based on the blend weightratio is determined as the ethylene content of the blend. In this case,it is preferable that the difference in the ethylene contents betweenthe two kinds of EVOH having the largest difference from each other is30 mol % or less and that the difference in the degree of saponificationis 10% or less. If these conditions are not satisfied, the transparencyof the resin composition may be inadequate. The difference in theethylene content is preferably 20 mol % or less, and more preferably 15mol % or less. The difference in the degree of saponification ispreferably 7% or less, and more preferably 5% or less. When themultilayered container comprising the resin composition of the presentinvention is desired to have higher and balanced impact delaminationresistance and gas barrier properties, it is preferable to blend an EVOH(c′1) having an ethylene content of 25 mol % or more and 55 mol % orless and a degree of saponification of 90% or more and less than 99% andan EVOH (c′2) having the ethylene content of 25 mol % or more and 55 mol% or less and a degree of saponification of 99% or more at a blendweight ratio c′1/c′2 of 5/95 to 95/5 for use.

The ethylene content and the degree of saponification of EVOH can beobtained by nuclear magnetic resonance (NMR).

The EVOH can contain a small amount of a monomer unit other than theethylene unit and the vinyl alcohol unit as a copolymer unit within arange not interfering with the objects of the present invention.Examples of a monomer constituting such a monomer unit include thefollowing compounds: α-olefins such as propylene, 1-butene, isobutene,4-methyl-1-pentene, 1-hexene, and 1-octene; unsaturated carboxylic acidssuch as itaconic acid, methacrylic acid, acrylic acid, and maleicanhydride, and their salts, their partial or complete esters, theirnitrites, their amides, and their anhydrides; vinylsilane compounds suchas vinyltrimethoxysilane, vinyltriethoxysilane,vinyltri(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane;unsaturated sulfonic acids and their salts; alkylthiols; andvinylpyrrolidones.

When a vinylsilane compound is contained in EVOH as a copolymerizedcomponent in an amount of 0.0002 to 0.2 mol % and the composition of thepresent invention containing the EVOH is formed into a multilayeredstructure together with a resin (e.g., polyester; hereinafter may bereferred to as “PES”) as a base resin by coextrusion molding orcoinjection molding, the consistency in the melt viscosity of the EVOHwith the base resin is improved, so that a uniformly molded product canbe produced. As the vinylsilane compound, vinyltrimethoxysilane andvinyltriethoxysilane can be used preferably.

Furthermore, EVOH containing a boron compound is also effective inimproving the melt viscosity of the EVOH, so that articles can beuniformly molded by coextrusion or coinjection molding. Examples of theboron compound include boric acids, boric acid esters, borates, andboron hydrides. Specifically, examples of the boric acids includeorthoboric acid (hereinafter may be referred to as “boric acid”),metaboric acid, and tetraboric acid. Examples of the boric acid estersinclude triethyl borate and trimethyl borate. Examples of the boratesinclude alkali metal salts and alkaline-earth metal salts of theabove-mentioned boric acids, borax, and the like. Among these compounds,orthoboric acid is preferable.

The content of the boron compound, if contained, is preferably in therange of 20 to 2000 ppm, and more preferably 50 to 1000 ppm, in terms ofthe boron element. With the addition of boron within this range, torquevariation in EVOH during melting by heating is suppressed. If the boroncontent is less than 20 ppm, this effect is minimal. If it exceeds 2000ppm, gelation tends to occur resulting in poor moldability.

It is also effective to add an alkali metal salt to the EVOH in anamount of 5 to 5000 ppm in terms of the alkali metal element in order toimprove interlayer adhesions and compatibility. The added amount of thealkali metal salt is preferably in the range of 20 to 1000 ppm, and morepreferably 30 to 500 ppm, in terms of the alkali metal element. Examplesof the alkali metal include lithium, sodium, potassium, and the like.Examples of the alkali metal salt include aliphatic carboxylates,aromatic carboxylates, phosphates, and metal complexes of alkali metals.Specifically, they include sodium acetate, potassium acetate, sodiumphosphate, lithium phosphate, sodium stearate, potassium stearate, asodium salt of ethylenediaminetetraacetic acid, and the like. Amongthese, sodium acetate, potassium acetate, and sodium phosphate arepreferable.

It is also preferable to add a phosphorus compound to the EVOH in anamount of 20 to 500 ppm, more preferably 30 to 300 ppm, and mostpreferably 50 to 200 ppm, in terms of the phosphoric acid radicals. Whena phosphorus compound is blended with the EVOH in the above range, thethermal stability of the EVOH can be improved. In particular, generationof gelled aggregates and coloring during long-duration melt molding canbe suppressed.

There is no particular limitation regarding the kind of phosphoruscompound added to the EVOH, and various kinds of acids such asphosphoric acid and phosphorous acid and salts thereof may be used.Phosphates may be in the form of primary phosphates, secondaryphosphates, or tertiary phosphates. There is no particular limitationregarding the cationic species of the phosphates, but the cationicspecies are preferably alkali metal and alkaline-earth metal. Amongthese, it is preferable to add the phosphorus compound in the form ofsodium dihydrogenphosphate, potassium dihydrogenphosphate, disodiumhydrogenphosphate, or dipotassium hydrogenphosphate.

A preferable melt flow rate (MFR) of the EVOH (210° C., 2160 g load;according to JIS K7210) is in the range of 0.1 to 100 g/10 min, morepreferably 0.5 to 50 g/10 min, and even more preferably 1 to 30 g/10min.

The kind of the polyamide resin (C2) as the gas barrier resin (C) is notspecifically limited. Examples thereof include: aliphatic polyamideswhich are homopolymers such as polycaproamide (Nylon-6),polyundecanamide (Nylon-11), polylaurolactam (Nylon-12),polyhexamethyleneadipamide (Nylon-6,6), and polyhexamethylenesebacamide(Nylon-6,10); aliphatic polyamides which are copolymers such as acaprolactam/laurolactam copolymer (Nylon-6/12), acaprolactam/aminoundecanoic acid copolymer (Nylon-6/11), acaprolactam/co-aminononanoic acid copolymer (Nylon-6/9), acaprolactam/hexamethylene adipamide copolymer (Nylon-6/6,6), and acaprolactam/hexamethylene adipamide/hexamethylene sebacamide copolymer(Nylon-6/6,6/6, 10); and aromatic polyamides such as polymetaxylyleneadipamide (MX-Nylon) and a hexamethylene terephthalamide/hexamethyleneisophthalamide copolymer (Nylon-6T/6I). These polyamide resins (C2) canbe employed alone or in combinations of two or more. Among these,polycaproamide (Nylon-6) and polyhexamethylene adipamide (Nylon-6,6) arepreferable in view of gas barrier properties.

Examples of the polyvinyl chloride resin (C3) include a homopolymer suchas a vinyl chloride homopolymer and a vinylidene chloride homopolymerand a copolymer containing vinyl chloride or vinylidene chloride andfurther containing vinyl acetate, a maleic acid derivative, a higheralkyl vinyl ether or the like.

Examples of the polyacrylonitrile resin (C4) include a homopolymer ofacrylonitrile and copolymers of acrylonitrile and an acrylic ester orthe like.

As the gas barrier resin (C), one of the above-described resins can beused, or two or more can be used in combination. Among those, thepolyvinyl alcohol resin (C1) is preferable and the EVOH having anethylene content of 5 to 60 mol % and a degree of saponification of 90%or more is more preferable.

It is also possible to blend to the gas barrier resin (C) a thermalstabilizer, an ultraviolet absorber, an antioxidant, a coloring agent, afiller, and other resins (e.g., polyamides and polyolefins) in advance,within a range not interfering with the objects of the presentinvention.

When the oxygen absorption resin composition of the present inventioncontains the gas barrier resin (C) as a resin component, in addition tothe thermoplastic resin (A), it is preferable to contain thethermoplastic resin (A) in a ratio of 30 to 1 wt % and to contain thegas barrier resin (C) in a ratio of 70 to 99 wt %, when the total weightof the thermoplastic resin (A) and the gas barrier resin (C) is 100 wt%. If the content of the gas barrier resin (C) is less than 70 wt %, thegas barrier properties of the resin composition with respect to oxygengas or carbon dioxide gas may deteriorate. On the other hand, if thecontent of the gas barrier resin (C) is more than 99 wt %, the oxygenscavenging function may deteriorate, because the content of thethermoplastic resin (A) is small. The content of the thermoplastic resin(A) is more preferably 20 to 2 wt %, even more preferably 15 to 3 wt %,and the content of the gas barrier resin (C) is more preferably 80 to 98wt %, and even more preferably 85 to 97 wt %.

(4) Compatibilizer (D)

The compatibilizer (D) is contained, if necessary, for the purpose ofimproving the compatibility of resins and allowing the resultant resincomposition to provide stable morphology, when the thermoplastic resin(A) and the gas barrier resin (C) are contained, or when another resin(E), which will be described later, is further contained in the resincomposition of the present invention. There is no limitation regardingthe kind of the compatibilizer (D), and the compatibilizer (D) can beselected as appropriate, depending on the combination of thethermoplastic resin (A), the gas barrier resin (C), and the like thatare to be employed.

For example, when the gas barrier resin (C) has a high polarity, such aspolyvinyl alcohol resin, a hydrocarbon polymer containing a polar groupor an ethylene-vinyl alcohol copolymer is preferable as thecompatibilizer (D). For example, when a hydrocarbon polymer containing apolar group is employed as the compatibilizer (D), a polyhydrocarbonmoiety in the polymer, the moiety accounting for the main portion,enhances the affinity between the compatibilizer (D) and thethermoplastic resin (A). The polar group in the compatibilizer (D)enhances the affinity between the compatibilizer (D) and the gas barrierresin (C). As a result, the resultant resin composition can be providedwith stable morphology.

Examples of a monomer that can form the polyhydrocarbon moiety thataccounts for the main portion of the hydrocarbon polymer containing apolar group include α-olefins such as ethylene, propylene, 1-butene,isobutene, 3-methyl pentene, 1-hexene, and 1-octene; styrenes such asstyrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene,4-propylstyrene, 4-tert-butylstyrene, 4-cyclohexylstyrene,4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene,2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene,monochlorostyrene, dichlorostyrene, methoxystyrene, andtert-butoxystyrene; vinylnaphthalenes such as 1-vinylnaphthalene,2-vinylnaphthalene; aromatic compounds containing a vinylene group suchas indene and acenaphthylene; and conjugated diene compounds such asbutadiene, isoprene, 2,3-dimethyl butadiene, pentadiene, and hexadiene.The hydrocarbon polymer may be derived from primarily one of thesemonomers, or may be derived from primarily two or more of thesemonomers.

The hydrocarbon polymer containing a polar group is prepared using oneor more of the above-listed monomers, as described later, and themonomer forms a polyhydrocarbon moiety corresponding to one of thefollowing polymers: an olefin copolymer such as polyethylene (very lowdensity, low density, linear low density, medium density, or highdensity polyethylene), ethylene-(meth)acrylic ester (methyl ester, ethylester, etc.) copolymer, ethylene-vinyl acetate copolymer, ethylene-vinylalcohol copolymer, polypropylene, ethylene-propylene copolymer; astyrene polymer such as polystyrene, styrene-acrylonitrile copolymer,styrene-acrylonitrile-butadiene copolymer, a styrene-diene blockcopolymer (e.g., styrene-isoprene block copolymer, styrene-butadienecopolymer, styrene-isoprene-styrene block copolymer, etc.), and ahydrogenated product thereof, a (meth)acrylate polymer such aspolymethyl acrylate, polyethyl acrylate, and polymethyl methacrylate; ahalogenated vinyl polymer such as polyvinyl chloride and vinylidenefluoride; a semi-aromatic polyester such as polyethylene terephthalateand polybutylene terephthalate; and an aliphatic polyester such aspolyvalerolactone, polycaprolactone, polyethylene succinate, andpolybutylene succinate. Among these, styrene polymers such asstyrene-diene block copolymers (e.g., styrene-isoprene block copolymer,styrene-butadiene copolymer, styrene-isoprene-styrene block copolymer,etc.), and a hydrogenated product thereof are preferable.

There is no particular limitation regarding the polar group contained inthe compatibilizer (D), but a functional group containing an oxygen atomis preferable. More specifically, the following groups are preferred:active hydrogen-containing polar groups (e.g., —SO₃H, —SO₂H, —SOH,—CONH₂, —CONHR, —CONH—, —OH, etc.), nitrogen-containing polar groupsthat are free from active hydrogen (e.g., —NCO, —OCN, —NO, —NO₂, —CONR₂,—CONR—, etc.), an epoxy group, carbonyl group-containing polar groups(e.g., —CHO, —COOH, —COOR, —COR, >C═O, —CSOR, —CSOH, etc.),phosphorus-containing polar groups (e.g., —P(OR)₂, —PO(OR)₂, —PO(SR)₂,—PS(OR)₂, —PO(SR)(OR), —PS(SR)(OR), etc.), boron-containing polar groupsand the like. In the above general formulae, R represents an alkylgroup, a phenyl group or an alkoxy group.

There is no particular limitation regarding the method for producing thehydrocarbon polymer containing the polar group. For example, thefollowing methods can be employed: 1) a method of copolymerizing amonomer that can form the polyhydrocarbon moiety and a monomercontaining the polar group (or a group that can form the polar group);2) a method of utilizing an initiator or a chain transfer agent havingthe polar group (or a group that can form the polar group) whenpolymerizing monomers that can form the polyhydrocarbon moiety; 3) amethod of subjecting a monomer that can form the polyhydrocarbon moietyto living polymerization and utilizing a monomer having the polar group(or a group that can form the polar group) as a terminator (i.e., an endtreatment agent); and 4) a method of polymerizing monomers that can formthe polyhydrocarbon moiety, followed by an introduction of a monomerhaving the polar group (or a group that can form the polar group) to areactive moiety of the resultant polymer, for example, a carbon-carbondouble bond moiety by a reaction. In the method 1, for copolymerization,any one of polymerization methods of random copolymerization, blockcopolymerization and graft copolymerization can be employed.

When the compatibilizer (D) is a hydrocarbon polymer, the followingpolar groups are particularly preferable: carboxyl groups such as acarboxyl group, a carboxylic acid anhydride group, and a carboxylategroup, and boron-containing polar groups such as a boronic acid group, aboronic ester group, boronic acid anhydride group and boronate groups.

When the polar group is a carboxyl group, the resultant resincomposition has a high thermal stability. As described above, when theresin composition contains an excessive amount of a transition metalsalt (B), the thermal stability of the resin composition may bedeteriorated, but when compatibilizer (D) having a carboxyl group iscontained together with the transition metal salt (B), the thermalstability of the resin composition can be maintained. The reason of thissignificant effect is not clear, but it seems that this is caused byinteraction between the compatibilizer (D) and the transition metal salt(B). When the polar group is a boron-containing polar group, thecompatibility of the thermoplastic resin (A) and the gas barrier resin(C) is improved significantly in the resultant resin composition, andstable morphology can be provided.

A compatibilizer (D) having such a polar group is disclosed in detail,for example, in Japanese Laid-Open Patent Publication No. 2002-146217.Among the compatibilizers disclosed in the publication, astyrene-hydrogenated diene block copolymer having a boronic ester groupis preferable.

As the compatibilizer (D), as described above, ethylene-vinyl alcoholcopolymers can also be used. In particular, when the gas barrier resin(C) is EVOH, its effect as the compatibilizer is exhibited sufficiently.Among these, an ethylene-vinyl alcohol copolymer having an ethylenecontent of 70 to 99 mol % and a degree of saponification of 40% or moreis preferable to improve the compatibility. The ethylene content is morepreferably 72 to 96 mol %, even more preferably 72 to 94 mol %. When theethylene content is less than 70 mol %, the affinity with thethermoplastic resin (A) may be deteriorated. When the ethylene contentis more than 99 mol %, the affinity with the EVOH may be deteriorated.Furthermore, the degree of saponification is preferably 45% or more.There is no limitation regarding the upper limit of the degree ofsaponification, and an ethylene-vinyl alcohol copolymer having a degreeof saponification of substantially 100% can be used. When the degree ofsaponification is less than 40%, the affinity with the EVOH may bedeteriorated.

The above-described compatibilizer (D) can be used alone or incombination of two or more.

When the oxygen absorption resin composition of the present inventioncontains the gas barrier resin (C) and the compatibilizer (D) as resincomponents, in addition to the thermoplastic resin (A), it is preferablethat the thermoplastic resin (A) is contained in a ratio of 29.9 to 1 wt%, the gas barrier resin (C) is contained in a ratio of 70 to 98.9 wt %,and the compatibilizer (D) is contained in a ratio of 29 to 0.1 wt %,when the total weight of the thermoplastic resin (A), the gas barrierresin (C) and the compatibilizer (D) is 100 wt %. If the content of thegas barrier resin (C) is less than 70 wt %, the gas barrier propertiesof the resin composition with respect to oxygen gas or carbon dioxidegas may deteriorate. On the other hand, if the content of the gasbarrier resin (C) is more than 98.9 wt %, the content of thethermoplastic resin (A) and the compatibilizer (D) is small, so that theoxygen scavenging function may deteriorate, and the stability of themorphology of the entire resin composition may be impaired. The contentof the thermoplastic resin (A) is more preferably 19.5 to 2 wt %, evenmore preferably 14 to 3 wt %. The content of the gas barrier resin (C)is more preferably 80 to 97.5 wt %, and even more preferably 85 to 96 wt%. The content of the compatibilizer (D) is more preferably 18 to 0.5 wt%, and even more preferably 12 to 1 wt %.

(5) Another Thermoplastic Resin (E) and Additives

The oxygen absorption resin composition of the present invention mayinclude a thermoplastic resin (E) other than the thermoplastic resin(A), the gas barrier resin (C) and the compatibilizer (D) within therange not interfering with the effects of the present invention.Examples of the thermoplastic resin (E) include, but are not limited to,polyolefins such as polyethylene, polypropylene, ethylene-propylenecopolymer, a copolymer including ethylene or propylene (e.g., acopolymer including ethylene or propylene and at least one of thefollowing monomers as a copolymerized unit: α-olefins such as 1-butene,isobutene, 4-methyl-1-pentene, 1-hexene, and 1-octene; unsaturatedcarboxylic acids such as itaconic acid, methacrylic acid, acrylic acid,and maleic anhydride, and their salts, their partial or complete esters,their nitriles, their amides, and their anhydrides; vinyl carboxylatessuch as vinyl formate, vinyl acetate, vinyl propionate, vinyl butylate,vinyl octanoate, vinyl dodecanoate, vinyl stearate, and vinylarachidonate; vinylsilane compounds such as vinyltrimethoxysilane;unsaturated sulfonic acids and their salts; alkylthiols; vinylpyrrolidones and the like), poly-4-methyl-1-pentene, and poly-1-butene;polyesters such as polyethylene terephthalate, polybutyleneterephthalate, and polyethylene naphthalate; polystyrene,polycarbonates, and polyacrylates. The thermoplastic resin (E) can becontained in a ratio of at most 10 wt % of the total weight of the resincomposition.

In the resin composition of the present invention, various additives canbe added within the range not interfering with the function and theeffects of the present invention. Examples of such additives includeantioxidants, plasticizers, thermal stabilizers (i.e., meltstabilizers), photoinitiators, deodorants, ultraviolet absorbers,antistatic agents, lubricants, colorants, fillers, drying agents,filling agents, pigments, dyes, processing aids, flame retarders,antifogging agents, or other polymer compounds. Such additives aredisclosed in detail, for example, in Japanese Laid-Open PatentPublication No. 2002-146217.

(6) Oxygen Absorption Resin Composition and Molded Product Using theSame

The oxygen absorption resin composition of the present inventioncontains the thermoplastic resin (A) and the transition metal salt (B),and if necessary, the gas barrier resin (C), the compatibilizer (D) andanother thermoplastic resin (E), and various additives as mentionedabove. The oxygen absorption rate of the resin composition of thepresent invention is preferably 0.01 ml/(g·day) or more, more preferably0.05 ml/(g·day) or more. Herein, the oxygen absorption rate is a volumeof oxygen that is absorbed by a film made of the resin composition perunit weight in a unit time, when the film is stored in the air with apredetermined volume. A specific method for measuring the oxygenabsorption rate will be shown in Examples described later. Thecomposition can be formed into a molded product having a desired shapeby mixing the components of the composition and molding, as describedlater.

When the oxygen absorption resin composition of the present invention isa composition containing the gas barrier resin (C), in addition to thethermoplastic resin (A) and the transition metal salt (B), the functionof the gas barrier resin (C) can be provided, and moreover, the oxygenscavenging function tend to be retained for a long period of time andgeneration and emission of odorous substance tend to be suppressed. Inthis way, the composition containing the gas barrier resin (C) retains ahigh oxygen scavenging ability for a longer time, and odor generated dueto the absorption of oxygen tends to be reduced compared with acomposition including only the thermoplastic resin (A) and thetransition metal salt (B). In particular, when the gas barrier resin (C)is a polyvinyl alcohol resin, especially, EVOH, generation of odor issuppressed to a very low level. The mechanism for this is not clear, butit can be theorized that it is more difficult for the gas barrier resinto transmit an odorous substance having a large molecular weight thanoxygen, and the polyvinyl alcohol resin is reacted with or absorbs theodorous substance.

In the oxygen absorption resin compositions of the present inventionthat contain a certain resin other than the thermoplastic resin (A),such as the gas barrier resin (C), it is recommended that particles ofthe thermoplastic resin (A) are dispersed in a matrix comprising theresin other than the thermoplastic resin (A) (i.e., at least one of thegas barrier resin (C), the compatibilizer (D), and the thermoplasticresin (E)), the transition metal salt (B), and various additives. Forexample, when the oxygen absorption resin composition of the presentinvention is essentially composed of the thermoplastic resin (A) and thegas barrier resin (C), it is recommended that particles of thethermoplastic resin (A) are dispersed in a matrix of the gas barrierresin (C). This form is preferable, because resultant molded productsmade of the composition of this form can easily maintain the oxygenscavenging performance and the gas barrier properties. Furthermore, thefunction of the resin other than the thermoplastic resin (A), such asthe gas barrier resin (C), can be provided. This also exhibits goodtransparency. In this case, it is preferable that the average particlesize of the thermoplastic resin (A) is 10 μm or less. When the averageparticle size is more than 10 μm, the area of the interface between thethermoplastic resin (A) and the resin other than the thermoplastic resin(A) (e.g., the gas barrier resin (C)) becomes small, so that the oxygengas barrier properties and the oxygen scavenging function may bedegraded. The average size of the particles of the thermoplastic resin(A) is preferably 5 μm or less, and more preferably 2 μm or less.

In order to realize the above-described embodiment and realize excellentgas barrier properties, oxygen scavenging performance and low odor, thenumber average molecular weight is preferably 1000 to 500000, morepreferably 5000 to 300000, and even more preferably 10000 to 250000, andparticularly preferably 40000 to 200000. It is also preferable that thethermoplastic resin (A) is substantially not cross-linked.

Furthermore, when the gas barrier resin (C) has a high polarity, such aspolyvinyl alcohol resin, it is preferable that the thermoplastic resinhas a hydrophilic functional group as described above such as hydroxylgroup, an alkoxy group having 1 to 10 carbon atoms, an amino group, analdehyde group, a carboxyl group, an epoxy group, an ester group, acarboxylic acid anhydride group, or a polar group containing boron(e.g., a boronic acid group, a boronic ester group, a boronic acidanhydride group, or a boronate group), etc. In particular, it ispreferable that thermoplastic resin has a hydroxyl group, an epoxy groupor an acid anhydride group.

Furthermore, when the oxygen absorption resin composition of the presentinvention contains a suitable amount of the compatibilizer (D), theabove-described effects can be obtained stably.

A preferable melt flow rate (MFR) (210° C., 2160 g load, according toJIS K7210) of the oxygen absorption resin composition of the presentinvention is 0.1 to 100 g/10 min, more preferably 0.5 to 50 g/10 min,and even more preferably 1 to 30 g/10 min. When the melt flow rate ofthe resin composition of the present invention fails to fall within theabove range, the processability in melt-molding may become poor in manycases.

The components of the resin composition of the present invention aremixed and formed into a desired product. The process for mixing thecomponents of the resin composition of the present invention is notlimited to a particular method. The components can be mixed in anyorder. For example, when mixing the thermoplastic resin (A), thetransition metal salt (B), the gas barrier resin (C) and thecompatibilizer (D), they can be mixed simultaneously. Alternatively, thethermoplastic resin (A), the transition metal salt (B) and thecompatibilizer (D) can be mixed, and then the mixture can be mixed withthe gas barrier resin (C). Alternatively, the thermoplastic resin (A)and the compatibilizer (D) can be mixed, and then the mixture can bemixed with and the transition metal salt (B) and the gas barrier resin(C). The transition metal salt (B) and the gas barrier resin (C) can bemixed, and then the mixture can be mixed with the thermoplastic resin(A) and the compatibilizer (D). Alternatively, the thermoplastic resin(A), the gas barrier resin (C) and the compatibilizer (D) can be mixed,and then the mixture can be mixed with the transition metal salt (B).The transition metal salt (B) and the compatibilizer (D) can be mixed,and then the mixture can be mixed with the thermoplastic resin (A) andthe gas barrier resin (C). Moreover, the mixture obtained by mixing thethermoplastic resin (A), the gas barrier resin (C) and thecompatibilizer (D) can be mixed with the mixture obtained by mixing thetransition metal salt (B) and the gas barrier resin (C).

As a specific method of mixing, melt-kneading is preferable because ofthe simplified process and the cost. In this case, it is preferable touse an apparatus with high kneading ability to allow the components tobe finely and uniformly dispersed, because this can provide good oxygenabsorption performance and good transparency, and can prevent gels andaggregates from being generated or mixed.

As the apparatus having a high kneading level, continuous kneaders suchas a continuous intensive mixer and a kneading type twin screw extruder(co-rotation or counter-rotation), a mixing roll, and a Ko-kneader;batch kneaders such as a high-speed mixer, a Banbury mixer, an intensivemixer, or a pressure kneader; an apparatus using a rotary disk having atrituration mechanism such as a stone mill, for example, the KCKKneading Extruder from KCK Co., Ltd.; a single screw extruder providedwith a kneading section (e.g., Dulmage and CTM); and a simple kneadersuch as a ribbon blender and a Brabender mixer can be used. Among theabove, continuous kneaders are preferable. Examples of commerciallyavailable continuous intensive mixers include FCM from Farrel Corp., CIMfrom The Japan Steel Works, Ltd., and KCM, LCM, and ACM from Kobe Steel,Ltd. It is preferable to employ an apparatus equipped with a singlescrew extruder downstream of such a kneader to perform kneading andextrusion pelletizing simultaneously. Also as a twin screw kneadingextruder equipped with a kneading disk or a kneading rotor, for example,TEX from Japan Steel Works, Ltd., ZSK from Werner & Pfleiderer Corp.,TEM from Toshiba Machine Co., Ltd., and PCM from Ikegai Tekko Co, Ltd.can be used. A single kneader may be used, or two or more kneaders maybe coupled for use.

The kneading temperature is generally in the range of 50 to 300° C. Itis preferable to perform extrusion at low temperatures with the hopperport sealed with nitrogen in order to prevent oxidation of thethermoplastic resin (A). A longer kneading period provides betterresults. However, considering the prevention of oxidation of thethermoplastic resin (A) and the production efficiency, the kneading timeis generally 10 to 600 seconds, preferably 15 to 200 seconds, even morepreferably 15 to 150 seconds.

The resin composition of the present invention can be molded intovarious molded products such as films, sheets, containers or otherpackaging materials by using various molding methods as appropriate. Inthis case, the resin composition of the present invention can besubjected to molding after being formed into pellets, or the componentsof the resin composition can be dry-blended, and subjected directly tomolding.

With respect to molding methods and molded products, for example, theresin composition of the present invention can be molded into films,sheets, pipes and the like by melt extrusion molding, into containers byinjection molding and into bottle-like hollow containers by blowmolding. As the blow molding, it is preferable to employ extrusion blowmolding where a parison is formed by extrusion molding and blown forobtaining a molded product, and injection blow molding where a preformis formed by injection molding and blown for obtaining a molded product.

In the present invention, the molded product produced by theabove-described molding methods may be composed of a single layer, butit is preferable that the molded product is in the form of amultilayered structure obtained by laminating a layer of the resincomposition of the present invention and other layers, in view ofproviding characteristics such as mechanical properties, water vaporbarrier properties, and further oxygen barrier properties.

Examples of a layer structure of the multilayered structure include x/y,x/y/x, x/z/y, x/z/y/z/x, x/y/x/y/x, and x/z/y/z/x/z/y/z/x, where xdenotes a layer made of a resin other than the resin composition of thepresent invention, y denotes the resin composition layer of the presentinvention, and z denotes an adhesive resin layer, but the structure isnot limited to these structures. In the case where a plurality of xlayers are provided, such layers may be made of the same kind of resinor of different kinds of resin. A recovered resin layer made of scrapsgenerated by trimming during molding may be separately formed, or suchrecovered resin may be blended in a layer made of another resin. Thethickness of the layers of the multilayered structure is not limited toa particular thickness, but the ratio of the thickness of the y layer tothe total thickness of all the layers is preferably 2 to 20%, in view ofthe moldability, the cost or the like.

A thermoplastic resin is preferable as a resin used for the x layer inview of the processability or the like. Examples of such a thermoplasticresin include, but are not limited to, polyolefins such as polyethylene,polypropylene, ethylene-propylene copolymer, a copolymer includingethylene or propylene (e.g., a copolymer including ethylene or propyleneand at least one of the following monomers as a copolymerized component:α-olefins such as 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, and1-octene; unsaturated carboxylic acids such as itaconic acid,methacrylic acid, acrylic acid, and maleic anhydride, and their salts,their partial or complete esters, their nitriles, their amides, andtheir anhydrides; vinyl carboxylates such as vinyl formate, vinylacetate, vinyl propionate, vinyl butylate, vinyl octanoate, vinyldodecanoate, vinyl stearate, and vinyl arachidonate; vinylsilanecompounds such as vinyltrimethoxysilane; unsaturated sulfonic acids andtheir salts; alkylthiols; vinyl pyrrolidones and the like),poly-4-methyl-1-pentene and poly-1-butene; polyesters such aspolyethylene terephthalate, polybutylene terephthalate, and polyethylenenaphthalate; polyamides such as poly ε-caprolactam, polyhexamethyleneadipamide, and polymetaxylylene adipamide; polyvinylidene chloride,polyvinyl chloride, polystyrene, polyacrylonitrile, polycarbonate, andpolyacrylate. Such a thermoplastic resin layer may be a non-orientedlayer or a layer subjected to uniaxial or biaxial orientation orrolling.

Among these thermoplastic resins, polyolefins are preferable because oftheir excellent moisture-resistance, mechanical properties, economy,heat sealing properties and the like. Polyesters are preferable becauseof excellent mechanical properties, heat resistance or the like.

On the other hand, there is no limitation regarding the adhesive resinused for the z layer, and any adhesive resin can be used, as long as itcan bind the layers to each other. For example, polyurethane orpolyester one-component or two-component curing adhesives, andcarboxylic acid-modified polyolefin resin are preferably used. Thecarboxylic acid-modified polyolefin resin is an olefin polymer or acopolymer containing an unsaturated carboxylic acid or an anhydridesthereof (e.g., maleic anhydride) as a copolymerized component or a graftcopolymer obtained by grafting an unsaturated carboxylic acid or ananhydride thereof to an olefin polymer or copolymer.

Among these, a carboxylic acid-modified polyolefin resin is morepreferable. In particular, when the x layer is a polyolefin resin, theadhesion with the y layer is good. Examples of such a carboxylicacid-modified polyolefin resin include a resin obtained by carboxylicacid modification of polyethylene (low density polyethylene (LDPE),linear low density polyethylene (LLDPE), or very low densitypolyethylene (VLDPE)), polypropylene, polypropylene copolymer; anethylene-vinyl acetate copolymer, and ethylene-(meth)acrylate (forexample, methyl acrylate or ethyl acrylate) copolymers.

Examples of the method for producing the multilayered structure include,but are not limited to, extrusion lamination, dry lamination,coinjection molding and coextrusion molding. The coextrusion moldingincludes coextrusion lamination, coextrusion sheet molding, blown filmcoextrusion, and coextrusion blow molding.

The sheet, film, parison and the like of the thus obtained multilayeredstructure may further be reheated at a temperature below the meltingpoint of the contained resin and stretched uniaxially or biaxially bythermoforming such as draw forming, rolling, pantographic orientation,blown film orientation or extrusion blow molding, so that stretchedmolded products can be obtained.

The molded products using the multilayered structure can be used invarious applications. In particular, when the multilayered structure isused as multilayered containers, the advantages provided by themultilayered structure are significantly prominent. Furthermore, amultilayered structure in which layers having high water vapor barrierproperties are provided on both sides of a layer made of the resincomposition of the present invention or on the side that becomes highlyhumid is preferable in that the retention period of the oxygenscavenging function of the multilayered structure is particularlyprolonged, and as a result, very high gas barrier properties can beretained for a long time. On the other hand, a multilayered containerhaving the resin composition layer as the innermost layer is preferablein that the oxygen scavenging function in the container can be exertedpromptly.

Furthermore, the resin composition of the present invention exhibitsgood transparency by selecting an appropriate resin. Thus, such acomposition is suitable for a packaging container whose content isclearly visible. Among such packaging containers, the following twoembodiments of packaging containers satisfy a strict requirement fortransparency and thus particularly receive a benefit from the resincomposition of the present invention. One embodiment is a containercomposed of a multilayered film having a total thickness of 300 μm orless and including a layer made of the resin composition of the presentinvention. The other embodiment is a multilayered container including atleast one layer made of the resin composition of the present inventionand at least one thermoplastic polyester (PES) layer. These containerswill be described below in this order.

The container composed of a multilayered film having a total thicknessof 300 μm or less and including a layer made of the resin composition ofthe present invention is a flexible container composed of a multilayeredstructure having a relatively small total thickness and generally isprocessed into the form of a pouch or the like. This container hasexcellent gas barrier properties, and further has a continuous oxygenscavenging function, and the production is simple, so that thiscontainer is very useful for packaging of a product that is highlysensitive to oxygen and susceptible to degradation.

In a thin multilayered film having a total thickness of 300 μm or less,even if the transparency is deteriorated over time, the extent is small,and consequently the transparency of the multilayered film container canbe maintained. The thickness of such a multilayered film is preferably300 μm or less, more preferably 250 μm or less, and even more preferably200 μm or less, to retain the good transparency and flexibility. On theother hand, in view of the mechanical strength as a container, the totalthickness of all layers is preferably 10 μm or more, more preferably 20μm or more, and even more preferably 30 μm or more.

When producing the multilayered container with a multilayered filmhaving a total thickness of 300 μm or less, there is no particularlimitation regarding the method for producing the multilayered film. Forexample, a multilayered film can be formed by laminating a layer of theresin composition of the present invention and a layer of anotherthermoplastic resin by techniques such as dry lamination or coextrusionlamination.

In the case of dry lamination, non-oriented films, uniaxially orientedfilms, biaxial oriented films, and rolled films can be used. Amongthese, a biaxially oriented polypropylene film, a biaxially orientedpolyethylene terephthalate film and a biaxially oriented polyε-caprolactam film are suitable because of their mechanical strength.The biaxially oriented polypropylene film is particularly preferablealso in view of good moisture-resistance. When non-oriented films oruniaxially oriented films are used, the laminated film may further bere-heated and stretched uniaxially or biaxially by thermoforming such asdraw forming, rolling, pantographic orientation, or blown filmorientation, so that an oriented multilayered film can be formed.

In order to seal the obtained multilayered container, it is preferableto form a layer made of a heat-sealable resin on at least one outermostlayer surface of the multilayered film in the process of producing themultilayered film. Examples of such resin include polyolefin such aspolyethylene and polypropylene.

The thus obtained multilayered film can be processed into, for example,a bag shape and thus can be used as a packaging container to be filledwith a material. Such a packaging container is flexible and convenient,and has good transparency and oxygen scavenging properties, so that itis very useful for packaging of materials that are susceptible todegradation in the presence of oxygen, especially for foods or the like.

The multilayered container including at least one layer made of theresin composition of the present invention and at least one layer madeof the PES layer has good gas barrier properties, and excellent oxygenscavenging function. Furthermore, good transparency can be provided byselecting an appropriate resin. For this reason, this multilayeredcontainer can be used in various forms such as bag-like containers,cup-like containers, and hollow molded containers. Among these, thisembodiment can be applied particularly well to hollow molded containers,especially bottles.

As the PES used for the multilayered container of the present inventionincluding the layer made of the thermoplastic resin composition of thepresent invention and the PES layer, condensation polymers includingaromatic dicarboxylic acids or alkyl esters thereof and diols as maincomponents are used. In particular, PES including ethylene terephthalateas the main component is preferable in attaining the purpose of thepresent invention. More specifically, the total proportion (mol %) of aterephthalic acid unit and an ethylene glycol unit is preferably 70 mol% or more, and more preferably 90 mol % or more, of the total moles ofall the structural units of the PES. If the total proportion of theterephthalic acid unit and the ethylene glycol unit is less than 70 mol%, the resultant PES is amorphous, so that the mechanical strength isinsufficient. In addition, when the PES is stretched and formed into acontainer and the contents are hot-filled in the container, the thermalcontraction is so large that it may not be put to practical use.Moreover, when solid-phase polymerization is carried out to reduceoligomers contained in the resin, the softened resin tends to stick,which makes production difficult. If necessary, the above PES maycontain a bifunctional compound unit other than the terephthalic acidunit and the ethylene glycol unit. More specifically, the PES maycontain a neopentylglycol unit, a cyclohexane dimethanol unit, acyclohexane dicarboxylic acid unit, an isophthalic acid unit, anaphthalenedicarboxylic acid unit or the like in the range in which theabove-described problems are not caused. There is no limitationregarding a method for producing such PES, and a known method can beselected as appropriate.

The method for producing the multilayered container of the presentinvention including at least one layer made of the resin composition andat least one PES layer is not specifically defined, but coinjection blowmolding is preferred in view of productivity. In coinjection blowmolding, the container is produced by subjecting a multilayeredcontainer precursor (i.e., a parison) obtained by coinjection molding tostretch blow molding.

In the coinjection molding, in general, the resins to constitute thelayers of the multilayered structure are guided to concentric nozzlesfrom two or more injection cylinders and are injected into a single moldsimultaneously or alternately at non-synchronized timings, and oneclamping operation is performed for molding. For example, parisons areproduced by, but not limited to, the following methods: (1) PES layersfor the inner and outer layers are first injected, then the resincomposition for the sandwiched layer is injected, and thus a moldedcontainer of a three-layered structure of PES/resin composition/PES isobtained; and (2) PES layers for the inner and outer layers are firstinjected, then the resin composition is injected, and the PES layer isinjected again simultaneously with the injection of the resincomposition or thereafter so that a molded container of a five-layeredstructure of PES/resin composition/PES/resin composition/PES isobtained. Moreover, an adhesive resin layer may be disposed between theresin composition layer and the PES layer in the above layeredstructures, if necessary.

Regarding the conditions for injection molding, the PES is preferablyinjected at a temperature in the range of 250 to 330° C., morepreferably 270 to 320° C., even more preferably 280 to 310° C. If theinjection temperature for PES is lower than 250° C., the PES is notsufficiently melted, and the resulting molded products may containnon-molten substances (i.e., fisheyes), worsening the appearance, andmoreover, causing the degradation of the mechanical strength of themolded products. In some extreme cases, the screw torque for the PESinjection may increase, so that the molding machine may have operationalmalfunctions. If the injection temperature for PES exceeds 330° C., PESmay be highly decomposed, which may lead to a lowered molecular weight,so that the mechanical strength of the molded products may be lowered.Moreover, the PES decomposition gives off some vapors of acetaldehydeand the like, and thus the properties of the materials filled in themolded products (e.g., molded containers) may be worsened. Moreover, theoligomers resulting from the PES decomposition may stain the moldsignificantly, and the resultant molded products may have a poorappearance.

The thermoplastic resin composition is preferably injected at atemperature in the range of 170 to 250° C., more preferably 180 to 240°C., and even more preferably 190 to 230° C. If the injection temperaturefor the resin composition is lower than 170° C., the resin compositiondoes not melt sufficiently, and the resulting molded products may havenon-molten substances (i.e., fisheyes), and thus their appearance may beworsened. In some extreme cases, the screw torque for the PES injectionmay increase, so that the molding machine may have operationalmalfunctions. On the other hand, if the injection temperature for theresin composition exceeds 250° C., oxidation of the thermoplastic resin(A) may proceed, so that the gas barrier properties and the oxygenscavenging function of the resin composition may be degraded. Inaddition, the molded products may be unfavorably colored and containgelled materials, so that the appearance of the resulting moldedproducts may be poor. Alternatively, the flow of the resin compositionbeing injected will be disordered or blocked by vapors generated throughdecomposition of the resin composition and by the gelled materials, sothat the layer of the resin composition may have failed areas. In someextreme cases, the gelled materials will make it impossible to continuethe injection molding operation. In order to suppress the progress ofthe oxidation of the composition during melting, it is preferable toseal the supply hopper with nitrogen.

The resin composition of the present invention may be first formed intopellets by melt-blending raw material components, and then the pelletsmay be supplied to the molding machine. Alternatively, the componentsmay be dry-blended, and then the dry blend may be fed to the moldingmachine.

The total thickness of the thus obtained parison is preferably in therange of 2 to 5 mm, and the total thickness of the resin compositionlayer or layers is preferably in the range of 10 to 500 μm in total.

The above-mentioned parison is directly in its high-temperature state,or after having been re-heated with a heating member such as a blockheater, an infrared heater, or the like, transferred to the stretchblowing stage. In the stretch blowing stage, the heated parison isstretched one- to five-fold in the machine direction, and thereafterblown one- to four-fold with compressed air or the like so that theinjection-blown molded multilayered container of the present inventioncan be produced. The temperature of the parison is preferably in therange of 75 to 150° C., more preferably 85 to 140° C., even morepreferably 90 to 130° C., and most preferably 95 to 120° C. If thetemperature of the parison exceeds 150° C., the PES easily crystallizes,so that the resultant container is whitened and its appearance maybecome poor. In addition, the delamination of the container willincrease unfavorably. On the other hand, if the temperature of theparison is less than 75° C., the PES may be crazed to be pearly, so thatthe transparency of the resulting container may be lost.

The total thickness of the body part of the thus obtained multilayeredcontainer of the present invention generally is in the range of 100 to2000 μm, preferably 150 to 1000 μm, and may vary depending on the use ofthe container. In this case, the total thickness of the resincomposition layer is preferably in the range of 2 to 200 μM, morepreferably 5 to 100 μm.

Thus, the multilayered containers including the layer made of the resincomposition of the present invention and the PES layer are obtained. Thecontainers may have good transparency and also have excellent gasbarrier properties and oxygen scavenging function, and an odoroussubstance is not generated by oxygen absorption. The containers aretherefore suitable for packaging materials susceptible to degradation inthe presence of oxygen, such as foods and medicines. Especially, theycan be used most suitably as containers for foods whose flavor isimportant or drinks such as beer.

Further, the resin composition of the present invention is suitably usedfor packing (e.g., gaskets) for containers, especially as gaskets forcontainer caps. In this case, there is no particular limitationsregarding the material of the cap body, and materials that are usedgenerally in the art, for example, a thermoplastic resin and a metal canbe used. The cap having a cap body provided with such a gasket hasexcellent gas barrier properties and a long-lasting oxygen scavengingfunction, and an odorous substance is not generated by oxygenabsorption. Therefore, this cap is very useful as a cap used forcontainers of a product that is highly sensitive to oxygen andsusceptible to degradation, foods whose flavor is particularlyimportant, drinks or the like.

EXAMPLES

Hereinafter, the present invention will be described in more detail byway of examples, but the present invention is not limited thereto. Inthe following examples and comparative examples, analysis and evaluationwere performed in the following manner.

(1) Molecular Structure of the Thermoplastic Resin (A)

The molecular structure was determined based on the spectrum obtained by¹H-NMR (nuclear magnetic resonance) measured using a deuteratedchloroform as a solvent (“JNM-GX-500 Model” manufactured by JEOL Ltd.was used).

(2) Ethylene Content and the Degree of Saponification of EVOH:

The ethylene content and the degree of saponification of EVOH werecalculated based on the spectrum obtained by ¹H-NMR measured using adeuterated dimethyl sulfoxide as a solvent (“JNM-GX-500 Model”manufactured by JEOL Ltd. was used).

Synthesis Example 1

Synthesis of Epoxy Group-Containing Polybutadiene (A-2)

As a raw material, polybutadiene (polybutadiene rubber “Nipol BR1220”manufactured by ZEON CORPORATION; hereinafter this polybutadiene isreferred to as polybutadiene (A-1)) was used. This resin had a numberaverage molecular weight of 160000, and contained cis-polybutadiene,trans-polybutadiene and 1,2-polybutadine in a molar ratio of 96/2/2. Theratio of the carbon-carbon double bonds in its side chains to the totalcarbon-carbon double bonds was 2% (i.e., 100×b/(a+b)=2, where a (mol/g)is the amount of the carbon-carbon double bonds in its main chain and b(mol/g) is the amount of the carbon-carbon double bonds in the sidechains).

To a 300 ml-separable flask provided with a condenser, a droppingfunnel, a thermometer and a mechanical stirrer, 25 g of thepolybutadiene (A-1), 250 g of cyclohexane and 0.32 g oftrioctylmethylammonium chloride were added, and were dissolvedcompletely therein while being stirred at 60° C. The resultant mixturewas heated to 70° C., and an aqueous solution of pH 3.1 that wasprepared by dissolving 0.15 g (0.05 mmol) of ammonium tungstate and 0.33g (3.3 mmol) of phosphoric acid in 20 g of water was added thereto.Then, while the resultant mixture was stirred vigorously at 70° C., 5.21g (0.046 mol) of a 30% hydrogen peroxide aqueous solution was addeddropwise over 4 hours, and the mixture was further stirred for 2 hours.After stirring was stopped, the mixture was allowed to separate into anorganic layer (i.e., a cyclohexane layer) and an aqueous layer at 60° C.The aqueous layer was removed, and the organic layer was washed with 100ml of water, then washed with 100 ml of a 5% sodium carbonate aqueoussolution, and further washed with 100 ml of water twice. Cyclohexane inthe organic layer was removed by distillation under a reduced pressureand the resultant residue was dried at 80° C. and a pressure of 800 Pafor 8 hours to give an epoxy group-containing polybutadiene (A-2)(yield: 33.2 g) as a product. The product was analyzed with ¹H-NMR. Theconversion ratio of the double bonds i.e., ratio of consumedcarbon-carbon double bonds) was 10%, the epoxidation ratio (i.e., epoxygroup formation ratio based on the amount of the original carbon-carbondouble bonds) was 9.85%, and thus, the selectivity ratio (i.e., epoxygroup formation ratio based on the amount of the consumed carbon-carbondouble bond) was 98.5%. The ratio of the carbon-carbon double bonds inthe side chains to the total carbon-carbon double bonds of this polymerwas 2%.

Synthesis Example 2 Synthesis of Hydroxyl Group-Containing Polybutadiene(A-3)

To a 300 ml-separable flask provided with a condenser, a droppingfunnel, a thermometer and a mechanical stirrer, 25 g of the epoxygroup-containing polybutadiene (A-2) that was obtained in SynthesisExample 1, 250 g of THF, and 10 g of 0.1% perchloric acid were added,and the mixture was stirred at 60° C. for 6 hours. After stirring wasstopped, the reaction mixture was cooled to 25° C. and neutralized with10 ml of a 5% ammonia aqueous solution. The resultant reaction mixturewas added to 500 g of methanol, and a precipitated product was collectedand dried at 80° C. and a pressure of 800 Pa for 8 hours. The obtainedhydroxyl group-containing polybutadiene (A-3) (yield: 23.5 g) wasanalyzed with ¹H-NMR. The conversion ratio of the epoxy group (i.e.,ratio of consumed epoxy group) was 100%, the hydrolysis ratio (i.e.,hydroxyl group formation ratio based on the amount of the consumedcarbon-carbon double bond) was 98.5%, and thus, the selectivity ratio(i.e., hydroxyl group formation ratio based on the amount of theconsumed epoxy group) was 100%. The ratio of the carbon-carbon doublebonds in the side chains to the total carbon-carbon double bonds of thispolymer was 2%.

Comparative Synthesis Example Synthesis of Styrene-Isoprene-StyreneBlock Copolymer (A-4)

First, 600 parts by volume of cyclohexane, 0.16 parts by volume ofN,N,N′,N′-tetramethylethylenediamine (TMEDA) and 0.094 parts by volumeof n-butyl lithium as an initiator were placed in an autoclave equippedwith a stirrer and previously purged with dry nitrogen. The temperatureof the mixture in the autoclave was raised to 50° C., and 4.25 parts byvolume of styrene monomer was fed thereto and was polymerized for 1.5hours. Next, the temperature was reduced to 30° C., and 120 parts byvolume of isoprene was fed thereto and polymerization reaction wascarried out for 2.5 hours. Furthermore, the temperature was raised againto 50° C., and 4.25 parts by volume of styrene monomer was fed thereto,and polymerization reaction was carried out for 1.5 hours.

Then,2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate and pentaerythritoltetrakis(3-laurylthiopropionate) asantioxidants were added to the resultant reaction mixture in an amountof 0.15 parts by weight each with respect to 100 parts by weight of thetotal amount of the styrene and isoprene. The reaction mixture waspoured into methanol to precipitate a product, which was separated anddried. Thus, a styrene-isoprene-styrene triblock copolymer (A-4) towhich the antioxidants were added was obtained.

The number average molecular weight of the thus obtained triblockcopolymer was 85000. The molecular weight of each styrene block in thecopolymer was 8500. The styrene content was 14 mol %. The ratio of thecarbon-carbon double bonds in the side chains to the total carbon-carbondouble bonds was 55%. The content of carbon-carbon double bonds in theobtained triblock copolymer was 0.014 eq/g, and the melt flow rate was7.7 g/10 min. The resin included 0.12% by weight of2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzy)-4-methylphenylacrylateand 0.12% by weight of pentaerythritoltetrakis(3-laurylthiopropionate).

Synthesis Example 3 Synthesis of Compatibilizer (D-1)

First, styrene-hydrogenated butadiene-styrene triblock copolymer was fedto a co-rotational twin screw extruder TEM-35B (manufactured by ToshibaMachine Co., Ltd.) at a rate of 7 kg/hour while purging the feeding portwith nitrogen at a rate of 1 L/min. The styrene-hydrogenatedbutadiene-styrene triblock copolymer had the following physicalproperties: weight average molecular weight=100400; styrene/hydrogenatedbutadiene=18/82 (weight ratio); 1,2-bond/1,4-bond molar ratio in thebutadiene units=47/53; hydrogenation ratio of the butadiene unit=97%,amount of double bond=430 μeq/g, melt index=5 g/10 minutes (230° C.,2160 g load); density=0.89 g/cm³. Then, a mixture ofborane-triethylamine complex (TEAB) and boric acid 1,3-butanediol ester(BBD) (weight ratio of TEAB/BBD=29/71) was supplied from a liquid feeder1 at a rate of 0.6 kg/hour, and 1,3-butanediol was supplied from aliquid feeder 2 at a rate of 0.4 kg/hour, and continuously kneaded.During the kneading, the pressure was regulated such that the gauges atvent 0.1 and vent 2 indicated about 20 mmHg. As a result, a triblockcopolymer (D-1) containing a boronic acid 1,3-butanediol ester group(BBDE) was obtained at a rate of 7 kg/hour from the discharge port. Theamount of the boronic acid 1,3-butanediol ester group in the copolymerwas 210 μeq/g.

The structure and the operation conditions of the twin screw extruderused for the reaction are as follows.

-   -   Screw diameter: 37 mmφ    -   L/D: 52 (15 blocks)    -   Liquid feeder: C3 (liquid feeder 1), C11 (liquid feeder 2)    -   Vent position: C6 (vent 1), C14 (vent 2)

Screw structure: Seal rings are used between C5 and C6, between C10 andC11 and at a position C12 Temperature setting: C1 water-cooling C2 to C3200° C. C4 to C15 250° C. die 250° C. Screw rotation: 400 rpm

Example 1.1

First, 100 parts by weight of the above-described polybutadiene (A-1)and 0.8484 parts by weight of cobalt (II) stearate (0.0800 parts byweight in terms of cobalt atoms) were dry-blended, and the blend wasmelted and kneaded, using a roller mixer (LABO PLASTOMIL MODEL R₁₀₀manufactured by Toyo Seiki Seisakusho Ltd.) at a screw rotation of 60rpm at 190° C. at a total resin amount of 70.59 g while purging thechamber with nitrogen, and the blend was taken out in bulk form after 5minutes. The obtained bulky product was cut into pellets so that resincomposition pellets made of polybutadiene (A-1) and cobalt (II) stearatewere obtained.

The obtained resin composition pellets were supplied to a compressionmolding machine (manufactured by Shindo Metal Industries) and extrudedat a temperature of 200° C. so that a sheet having a thickness of 100 μmwas obtained. The obtained sheet was cut to obtain a sample sheet ofabout 0.1 g and the sheet was weighed precisely. Then, this sample sheetwas rolled 5 hours after the sheet formation and placed in a standardbottle having an internal volume of 260 ml that was filled with 50% RHair of 23° C. The air in the standard bottle contained oxygen andnitrogen at a volume ratio of 21:79. Then, 5 ml of water was added tothe standard bottle, and the opening of the standard bottle was sealedwith a multilayered sheet including an aluminum layer using an epoxyresin, and was stored at 60° C. After the sealing, the inner air wassampled with a syringe periodically to measure the oxygen concentrationof the air by gas chromatography. The small hole formed through themultilayered sheet during measurement was sealed with the epoxy resinevery time the hole was formed. The oxygen decrease amount wascalculated from the volume ratio of oxygen to nitrogen obtained bymeasurement, and thus, the oxygen absorption amount of the resincomposition in a 100% RH atmosphere at 60° C. was obtained. FIG. 1 andTable 1.1 show the oxygen absorption amount (cumulative amount) of oneday (24 hours), four days (96 hours), seven days (168 hours) and 14 days(336 hours) after the sealing. The oxygen absorption rate was calculatedbased on the results of 4 days after and 7 days after the start of themeasurement, and the rate was 15.0 ml/(g·day). Table 1.1 shows theresults.

Separately, the same sheet was cut to obtain a sample sheet of about 1 gand the sheet was weighed precisely. Then, this sample sheet was rolled5 hours after the sheet formation and placed in a standard bottle havingan internal volume of 85 ml that was filled with 50% RH air of 23° C.Then, 1 ml of water was added to the standard bottle, and the opening ofthe standard bottle was sealed with a multilayered sheet including analuminum layer using an epoxy resin, and was stored at 60° C. for 2weeks. Then, 10 ml of headspace gas of the bottle was sampled with agas-tight syringe, and the gas was collected and concentrated in aTENAX-TA tube at −40° C. The collected gas was desorbed by rapid heatingat 320° C. and introduced to GC/MS. The concentration and theintroduction to GC/MS of the generated gas were performed, using aconcentrating apparatus, Head Space Sampler JHS-100A.

The measurement conditions of GC/MS were as follows.

-   -   Heat desorption apparatus: Head Space Sampler JHS-100A        (manufactured by Japan Analytical Industry Co., Ltd)    -   Desorption temperature: 320° C., 25 sec.    -   MS apparatus: mass spectrometer JMS SX102A (manufactured by JEOL        Ltd.)    -   Data processing: data processing system MS-MP7000 (manufactured        by JEOL Ltd.)    -   GC apparatus: HP5890 (manufactured by Hewlett Packard)    -   Carrier gas: helium 20 ml/min    -   Column: Pora PROT Q 25 m×0.32 mmID    -   Column temperature: 80° C. to 250° C. (temperature increase        rate: 8° C./min)    -   Inlet temperature: 270° C.    -   Separator temperature: 270° C.

Acetone gas was collected in a vacuum collecting bottle, and dilutedwith nitrogen gas to prepare a standard gas (concentration: 4 μg/ml to 5μg/ml). By using this standard gas, a calibration curve was prepared.This calibration curve was used for the calculation of each of theamounts of gases shown in Table 1.2. The weight of various gasesgenerated and contained in the head space was converted to a gas weightper unit weight of the measurement sample based on the followingequation, and the resultant value was taken as an amount of a generatedgas (gas analysis value: unit ppm).

-   -   amount of gas generated (ppm=μg/g)=detected amount        (μg)×(85/10)/1    -   85: volume (ml) of the sample bottle    -   10: volume of head space gas (ml)    -   1: total amount (g) of sample sheet

Table 1.2 shows the results of the gas analysis value.

Example 1.2

Resin composition pellets were obtained and a sheet was prepared so thatthe oxygen absorption amount was obtained in the same manner as inExample 1.1 except that the hydroxyl group-containing polybutadiene(A-3) obtained in Synthesis Example 2 was used as the thermoplasticresin (A). FIG. 1 and Table 1.1 show the results. The oxygen absorptionrate calculated based on the results of 4 days after and 7 days afterthe start of the measurement was 13.3 ml/(g·day). Furthermore, analysisregarding the generated gas was performed in the same manner as inExample 1.1. Table 1.2 shows the results.

Example 1.3

Resin composition pellets were obtained and a sheet was prepared in thesame manner as in Example 1.1 except that cis/trans-1,4 polybutadieneavailable from Scientific Polymer Products, INC. was used as thethermoplastic resin (A), instead of the polybutadiene (A-1). Using thissheet, analysis regarding a generated gas was performed in the samemanner as in Example 1.1. Table 1.2 shows the results. In thecis/trans-1,4-polybutadiene available from Scientific Polymer Products,INC, the ratio of the carbon-carbon double bonds in the side chains tothe total carbon-carbon double bonds was 9%.

Comparative Example 1

Resin composition pellets were obtained and a sheet was prepared so thatthe oxygen absorption amount was obtained in the same manner as inExample 1.1 except that the styrene-isoprene-styrene block copolymer(A-4) obtained in the comparative synthesis example was used as thethermoplastic resin (A). FIG. 1 and Table 1.1 show the results. Theoxygen absorption rate calculated based on the results of 4 days afterand 7 days after the start of the measurement was 8.7 ml/(g·day).Furthermore, analysis regarding the generated gas was performed in thesame manner as in Example 1.1. Table 1.2 shows the results. TABLE 1.1Oxygen absorption rate Oxygen absorption (ml/g) ml/ Resin(A) 1 day 4days 7 days 14 days (g · day) Example 1.1 PBd 114 151 196 228 15.0Example 1.2 PBd-OH 120 160 200 210 13.3 Com. Ex. 1 SIS 99 153 179 2028.7PBd: Polybutadiene(A-1)PBd-OH: Hydroxyl group containing polybutadiene (A-3)SIS: Styrene-isoprene-styrene block copolymer (A-4)

TABLE 1.2 Com. Generated gas Example 1.1 Example 1.2 Example 1.3 Ex. 1Acetone 0.7 0.4 2.1 9.3 Methyl ethyl ketone 4.9 4.3 5.3 5.6Propionaldehyde ND ND 0.3 0.7 Furans 4.9 3.2 8.0 10.9 Propene 0.2 0.40.5 0.8 Butene 0.5 1.2 0.6 4.2 Cyclohexane ND ND ND 0.3Methylcyclobutane ND ND ND 0.5Unit: ppmND: Not determined

Example 2.1

In Examples 2.1 to 2.5 and Comparative Example 2 below, EVOH having thefollowing composition and properties (EVOH containing a phosphoruscompound and a sodium salt; hereinafter referred to as “EVOH (C-1)”) wasused as the gas barrier resin (C).

-   -   Ethylene content: 32 mol %    -   Saponification degree: 99.6%    -   MFR: 3.1 g/10 minutes (210° C., 2160 g load)    -   Phosphoric acid content: 100 ppm (in terms of phosphoric acid        radicals)    -   Sodium salt content: 65 ppm (in terms of sodium)    -   Melting point: 183° C.    -   Oxygen transmission rate: 0.4 ml·20 μm/(m²·day·atm) in 65% RH at        20° C.

First, 90 parts by weight of the above-described EVOH(C-1), 10 parts byweight of the polybutadiene (A-1) and 0.8484 parts by weight of cobalt(II) stearate (0.0800 parts by weight in terms of cobalt atoms) weredry-blended, and the blend was melted and kneaded, using a roller mixer(LABO PLASTOMIL MODEL R₁₀₀ manufactured by Toyo Seiki Seisakusho Ltd.)at a screw rotation of 60 rpm at 200° C. at a total resin amount of70.59 g while purging the chamber with nitrogen and taken out in a formof a bulk after 5 minutes. The obtained bulky product was cut intopellets so that resin composition pellets composed of EVOH(C-1), thepolybutadiene (A-1) and cobalt (II) stearate were obtained.

The obtained resin composition pellets were supplied to a compressionmolding machine (manufactured by Shindo Metal Industries) and extrudedat a temperature of 210° C. so that a sheet having a thickness of 100 μmwas obtained. Observation of the cutting plane of the sheet through anelectron microscope confirmed that the polybutadiene (A-1) was dispersedgenerally in the form of a particle having a size of about 1 to 5 μm inthe matrix of the EVOH(C-1).

This sheet was cut to obtain a sample sheet of about 0.5 g and the sheetwas weighed precisely. Then, this sample sheet was rolled and placed ina standard bottle, and was stored at 60° C. as in Example 1.1. Then, theoxygen amount was measured so as to obtain the oxygen absorption amountof the resin composition in a 100% RH atmosphere at 60° C. in the samemanner as in Example 1.1. FIG. 2 and Table 2.1 show the results. Whenthe oxygen absorption rate was calculated based on the results of 2 daysafter and 7 days after the start of the measurement, it was 1.9ml/(g-day). Table 2.1 shows the results.

Next, Measurement was performed in the same manner as above except thatthe storage temperature was 23° C., and thus, the oxygen absorptionamount of the resin composition in a 100% RH atmosphere at 23° C. wasobtained. FIG. 3 and Table 2.2 show the results. When the oxygenabsorption rate was calculated based on the results of 3 days after and8 days after the start of the measurement, it was 1.1 ml/(g·day). Table2.2 shows the results.

Example 2.2

A sheet made of a resin composition was obtained in the same manner asin Example 2.1 except that the epoxy group-containing polybutadiene(A-2) obtained in Synthesis Example 1 was used as the thermoplasticresin (A). Observation of the cutting plane of the sheet through anelectron microscope confirmed that the epoxy group-containingpolybutadiene (A-2) was dispersed generally in the form of a particlehaving a size of about 1 to 2 μm in the matrix of the EVOH(C-1). Then,the oxygen absorption amount of the resin composition was obtained inthe same manner as in Example 2.1. FIGS. 2 and 3 and Tables 2.1 and 2.2show the results. The oxygen absorption rate was obtained in the samemanner as in Example 2.1. Tables 2.1 and 2.2 show the results.

Example 2.3

A sheet made of a resin composition was obtained in the same manner asin Example 2.1 except that the hydroxyl group-containing polybutadiene(A-3) was used as the thermoplastic resin (A). Observation of thecutting plane of the sheet through an electron microscope confirmed thatthat the hydroxyl group-containing polybutadiene (A-3) was dispersedgenerally in the form of a particle having a size of about 1 to 2 μm inthe matrix of the EVOH(C-1). Then, the oxygen absorption amount of theresin composition was obtained in the same manner as in Example 2.1.FIGS. 2 and 3 and Tables 2.1 and 2.2 show the results. The oxygenabsorption rate was obtained in the same manner as in Example 2.1.Tables 2.1 and 2.2 show the results.

Example 2.4

A sheet made of a resin composition was obtained in the same manner asin Example 2.1 except that polybutadiene (number average molecularamount: 45000, the ratio of carbon-carbon double bonds in its sidechains to the total carbon-carbon double bonds: 5%, hereinafter,referred to as “polybutadiene (A-5)) was used as the thermoplastic resin(A). Observation of the cutting plane of the sheet through an electronmicroscope confirmed that the polybutadiene (A-5) was dispersedgenerally in the form of a particle having a size of about 1 to 2 μm inthe matrix of the EVOH(C-1). Then, the oxygen absorption amount of theresin composition was obtained in the same manner as in Example 2.1.FIGS. 2 and 3 and Tables 2.1 and 2.2 show the results. The oxygenabsorption rate was obtained in the same manner as in Example 2.1.Tables 2.1 and 2.2 show the results.

Example 2.5

A sheet made of a resin composition was obtained in the same manner asin Example 2.1 except that polybutadiene “Polyoil 130” (A-6)manufactured by ZEON CORPORATION (hereinafter, this polybutadiene isreferred to as polybutadiene (A-6)) was used as the thermoplastic resin(A). Observation of the cutting plane of the sheet through an electronmicroscope confirmed that the polybutadiene (A-6) was dispersedgenerally in the form of a particle having a size of about 1 to 10 μm inthe matrix of the EVOH(C-1). Then, the oxygen absorption amount of theresin composition was obtained in the same manner as in Example 2.1.FIGS. 2 and 3 and Tables 2.1 and 2.2 show the results. The oxygenabsorption rate was obtained in the same manner as in Example 2.1.Tables 2.1 and 2.2 show the results. The above-mentioned polybutadiene(A-6) had a number average molecular amount of 3000 and a ratio ofcarbon-carbon double bonds in its side chains to the total carbon-carbondouble bonds of 1%.

Comparative Example 2

A sheet made of a resin composition was obtained in the same manner asin Example 2.1 except that the above-described styrene-isoprene-styreneblock copolymer (A-4) was used as the thermoplastic resin (A).Observation of the cutting plane of the sheet through an electronmicroscope confirmed that the styrene-isoprene-styrene block copolymer(A-4) was dispersed generally in the form of a particle having a size ofabout 1 to 2 μm in the matrix of the EVOH(C-1). Then, the oxygenabsorption amount of the resin composition was obtained in the samemanner as in Example 2.1. FIGS. 2 and 3 and Tables 2.1 and 2.2 show theresults. The oxygen absorption rate was obtained in the same manner asin Example 2.1. Tables 2.1 and 2.2 show the results. TABLE 2.1 OxygenOxygen A/C*¹ absorption (ml/g)*² absorption (weight 7 14 rate Resin(A)ratio) 2 days days days ml/(g · day) Example 2.1 PBd(1) 10/90 26.2 35.638.6 1.9 Example 2.2 Ep-PBd 10/90 19.7 28.3 29.0 1.7 Example 2.3 PBd-OH10/90 24.9 35.9 37.7 2.2 Example 2.4 PBd(2) 10/90 32.8 42.1 45.0 1.9Example 2.5 PBd(3) 10/90 19.5 27.3 30.0 1.6 Com. Ex. 2 SIS 10/90 22.125.2 27.8 0.6PBd(1): Polybutadiene (A-1)Ep-PBd: Epoxy group-containing polybutadiene (A-2)PBd-OH: Hydroxyl group-containing polybutadiene (A-3)PBd(2): Polybutadiene (A-5)PBd(3): Polybutadiene (A-6)SIS: Styrene-isoprene-styrene block copolymer (A-4)*¹Weight ratio of thermoplastic resin (A) and gas barrier resin (C)*²Oxygen absorption amount in 100% RH at 60° C.,

TABLE 2.2 Oxygen absorption rate Oxygen absorption (ml/g)*¹ ml/ 3 days 8days 15 days 22 days 29 days (g · day) Example 2.1 5.0 10.5 16.9 21.625.9 1.1 Example 2.2 3.4 8.1 13.4 17.3 21.1 0.9 Example 2.3 8.0 13.520.5 27.5 34.5 1.1 Example 2.4 10.1 17.0 22.8 30.5 42.1 1.4 Example 2.52.8 7.5 11.5 15.1 18.4 0.9 Com. Ex. 2 3.4 7.7 12.2 15.4 20.0 0.9*¹Oxygen absorption amount in 100% RH at 23° C.

Example 3.1

First, 95 parts by weight of EVOH(C-1), 5 parts by weight ofpolybutadiene (A-1) and 0.8484 parts by weight of cobalt (II) stearate(0.0800 parts by weight in terms of cobalt atoms) were dry-blended, andthe blend was extruded into pellets using a 25 mm φ twin screw extruder(LABO PLASTOMIL MODEL 15C300 manufactured by Toyo Seiki Seisakusho Ltd.)at a screw rotation of 100 rpm at 210° C. at an extruded resin amount of6 kg/hour. Then, the pellets were dried under a reduced pressure at 40°C. for 16 hours, and thus resin composition pellets composed ofEVOH(C-1), polybutadiene (A-1) and cobalt (II) stearate were obtained.

The obtained resin composition pellets were subjected to extrusionmolding at a temperature of 210° C. so that a film having a thickness of20 μm was obtained. Observation of the cutting plane of the film throughan electron microscope confirmed that the polybutadiene (A-1) wasdispersed generally in the form of a particle having a size of about 1to 5 μm in the matrix of the EVOH(C-1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 2.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 2.1. Theoxygen absorption rate in a 100% RH atmosphere at 23° C. was calculatedbased on the results of 3 days after and 6 days after the start of themeasurement. Tables 3.1 and 3.2 show the results. Furthermore, the odorevaluation was performed in the manner described below.

Odor Evaluation

The film was cut to obtain a sample film of about 1 g and the film wasweighed precisely. Then, this sample film was rolled 5 hours after thefilm formation and placed in a standard bottle having an internal volumeof 85 ml that was filled with 50% RH air at 23° C. Then, 1 ml of waterwas added to the standard bottle, and the opening of the standard bottlewas sealed with a multilayered film including an aluminum layer using anepoxy resin, and was stored at 60° C. for two weeks. Thereafter, theodor of headspace gas of the samples was subjected to sensory evaluationby 5 test persons.

Each of the 5 test persons evaluated that almost no odor present in theheadspace gas. The results was shown in Table 3.2, in which ⊚ indicatesthat almost no odor present in the headspace gas.

Example 3.2

First, resin composition pellets were obtained in the same manner as inExample 3.1 except that 90 parts by weight of EVOH(C-1), 10 parts byweight of polybutadiene (A-1) and 0.8484 parts by weight of cobalt (II)stearate were used, and the resultant pellets were subjected toextrusion molding so that a film was obtained. Observation of thecutting plane of the film through an electron microscope confirmed thatthe polybutadiene (A-1) was dispersed generally in the form of aparticle having a size of about 1 to 5 μm in the matrix of theEVOH(C-1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 3.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 3.1.Tables 3.1 and 3.2 show the results. Furthermore, the odor evaluationwas performed in the same manner as in Example 3.1. Each of the 5 testpersons evaluated that almost no odor present in the headspace gas.Table 3.2 shows the results.

Example 3.3

First, resin composition pellets were obtained in the same manner as inExample 3.1 except that 93 parts by weight of EVOH(C-1), 5 parts byweight of polybutadiene (A-1), 2 parts by weight of the compatibilizer(D-1) and 0.8484 parts by weight of cobalt (II) stearate were used, andwas extrusion-molded so that a film was obtained. Observation of thecutting plane of the film through an electron microscope confirmed thatthe polybutadiene (A-1) was dispersed generally in the form of aparticle having a size of about 1 to 2 μm in the matrix of theEVOH(C-1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 3.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 3.1.Tables 3.1 and 3.2 show the results. Furthermore, the odor evaluationwas performed in the same manner as in Example 3.1. Each of the 5 testpersons evaluated that almost no odor present in the headspace gas.Table 3.2 shows the results.

Example 3.4

First, resin composition pellets were obtained in the same manner as inExample 3.1 except that a polyethylene resin “Mirason 11” (C-2)manufactured by Mitsui Chemicals, Inc. was used instead of the EVOH(C-1), and was extrusion-molded so that a film was obtained. Observationof the cutting plane of the film through an electron microscopeconfirmed that the polybutadiene (A-1) was dispersed generally in theform of a particle having a size of about 1 to 5 μm in the matrix of thepolyethylene resin (C1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 3.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 3.1.Tables 3.1 and 3.2 show the results. Furthermore, the odor evaluationwas performed in the same manner as in Example 3.1. Each of the 5 testpersons evaluated that odor present in lower level in the headspace gas.The results was shown in Table 3.2, in which ◯ indicates that odorpresent in lower level in the headspace gas. Table 3.2 shows theresults.

Comparative Example 3.1

First, resin composition pellets were obtained in the same manner as inExample 3.1 except that styrene-isoprene-styrene block copolymer (A-4)was used as the thermoplastic resin (A), and the pellets were subjectedto extrusion molding so that a film was obtained. Observation of thecutting plane of the film through an electron microscope confirmed thatthe copolymer (A-4) was dispersed generally in the form of a particlehaving a size of about 1 to 2 μm in the matrix of the EVOH(C-1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 3.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 3.1.Tables 3.1 and 3.2 show the results. Furthermore, the odor evaluationwas performed in the same manner as in Example 3.1. Each of the 5 testpersons evaluated that disagreeable odor present in the headspace gas.The results was shown in Table 3.2, in which x indicates thatdisagreeable odor present in the headspace gas. Table 3.2 shows theresults.

Comparative Example 3.2

First, resin composition pellets were obtained in the same manner as inExample 3.1 except that mix-polybutadiene (“Nipol BR₁₂₄₂” manufacturedby ZEON CORPORATION, 1,4-butadine/1,2-butadine=87.5/12.5; hereinafterreferred to “polybutadiene (A-7)”) was used as the thermoplastic resin(A), and the pellets were subjected to extrusion molding so that a filmwas obtained. Observation of the cutting plane of the film through anelectron microscope confirmed that the polybutadiene (A-7) was dispersedgenerally in the form of a particle having a size of about 1 to 5 μm inthe matrix of the EVOH(C-1).

Using this film, the oxygen absorption amount of the resultant resincomposition was obtained in the same manner as in Example 3.1. FIGS. 4and 5 and Tables 3.1 and 3.2 show the results. Furthermore, the oxygenabsorption rate was calculated in the same manner as in Example 3.1.Tables 3.1 and 3.2 show the results. Furthermore, the odor evaluationwas performed in the same manner as in Example 3.1. Each of the 5 testpersons evaluated that odor present in the headspace gas. The resultswas shown in Table 3.2, in which Δ indicates that odor present in theheadspace gas. Table 3.2 shows the results. TABLE 3.1 CompatibilizerA/C/D/E*¹ Oxygen absorption (ml/g)*² Oxygen absorption rate Resin(A) (D)Resin(E) (weight ratio) 2 days 7 days 14 days ml/(g · day) Example 3.1PBd —  5/95/0/0 8.2 12.4 15.2 0.8 Example 3.2 PBd — 10/90/0/0 12.7 21.426.6 1.7 Example 3.3 PBd D-1  5/93/2/0 14.6 19.7 22.4 1.0 Example 3.4PBd — PE  5/0/0/95 10.1 13.5 17.3 0.7 Com. Ex. 3.1 SIS —  5/95/0/0 16.417.6 18.3 0.2 Com. Ex. 3.2 mix-PBd —  5/95/0/0 9.7 14.0 16.2 0.9PBd: Polybutadiene (A-1)SIS: Styrene-isoprene-styrene block copolymer (A-4)mix-PBd: Polybutadiene (A-7)*¹Weight ratio of thermoplastic resin (A), gas barrier resin (C),compatibilizer (D), and other resin (E)*²Oxygen absorption amount in 100% RH at 60° C.

TABLE 3.2 Oxygen Oxygen absorption (ml/g)*¹ absorption 6 10 14 rate Odor3 days days days days ml/(g · day) evaluation Example 3.1 1.7 3.0 4.86.9 0.4 ⊚ Example 3.2 1.5 3.1 6.2 11.0 0.5 ⊚ Example 3.3 2.5 8.2 9.610.4 1.9 ⊚ Example 3.4 2.2 4.0 5.1 8.2 0.6 ◯ Com. Ex. 3.1 1.8 5.7 8.512.4 1.3 X Com. Ex. 3.2 2.4 3.9 5.3 7.6 0.5 Δ*¹Oxygen absorption amount in 100% RH at 23° C.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments disclosedin this application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1. An oxygen absorption resin composition comprising a thermoplasticresin (A) having carbon-carbon double bonds substantially in its mainchain and a transition metal salt (B).
 2. The oxygen absorption resincomposition of claim 1, wherein in the thermoplastic resin (A), thefollowing inequality (1) is satisfied:100×b/(a+b)≦7  (1) wherein a (mol/g) is an amount of the carbon-carbondouble bonds in its main chain, and b (mol/g) is an amount of thecarbon-carbon double bonds in its side chain.
 3. The oxygen absorptionresin composition of claim 1 or 2, wherein the thermoplastic resin (A)comprises at least one of the units represented by formula (I) andformula (II):

wherein R₁, R₂, R₃ and R₄ are the same or different, a hydrogen atom, analkyl group that may be substituted, an aryl group that may besubstituted, an alkylaryl group that may be substituted, —COOR₅, —OCOR₆,a cyano group or a halogen atom, and R₃ and R₄ may together form a ringvia a methylene group or an oxymethylene group, where R₅ and R₆ are analkyl group that may be substituted, an aryl group that may besubstituted or an alkylaryl group that may be substituted.
 4. The oxygenabsorption resin composition of any one of claims 1 to 3, wherein thethermoplastic resin (A) is at least one resin selected from the groupconsisting of polybutadiene, polyisoprene, polychloroprene, andpolyoctenylene.
 5. The oxygen absorption resin composition of any one ofclaims 1 to 3, wherein the thermoplastic resin (A) comprises at leastone of the units represented by formula (I) and formula (II):

wherein R₁, R₂, R₃ and R₄ are hydrogen atoms.
 6. The oxygen absorptionresin composition of any one of claims 1 to 5, wherein the thermoplasticresin (A) is at least one resin selected from the group consisting ofpolybutadiene and polyoctenylene.
 7. The oxygen absorption resincomposition of any one of claims 1 to 6, wherein the transition metalsalt (B) is at least one metal salt selected from the group consistingof an iron salt, a nickel salt, a copper salt, a manganese salt and acobalt salt.
 8. The oxygen absorption resin composition of any one ofclaims 1 to 7, wherein the oxygen absorption rate is at least 0.01ml/(g·day).
 9. The oxygen absorption resin composition of any one ofclaims 1 to 8, further comprising a gas barrier resin (C) having anoxygen transmission rate of 500 ml·20 μm/(m²·day·atm) or less in 65% RHat 20° C.
 10. The oxygen absorption resin composition of claim 9,wherein the gas barrier resin (C) is at least one resin selected fromthe group consisting of a polyvinyl alcohol resin, a polyamide resin, apolyvinyl chloride resin and a polyacrylonitrile resin.
 11. The oxygenabsorption resin composition of claim 9, wherein the gas barrier resin(C) is an ethylene-vinyl alcohol copolymer having an ethylene content of5 to 60 mol % and a saponification degree of 90% or more.
 12. The oxygenabsorption resin composition of any one of claims 9 to 11, wherein thegas barrier resin (C) is contained in an amount of 70 to 99 wt % and thethermoplastic resin (A) is contained in an amount of 30 to 1 wt %, whenthe total weight of the thermoplastic resin (A) and the gas barrierresin (C) is determined to be 100 wt %.
 13. The oxygen absorption resincomposition of any one of claims 9 to 12, further comprising acompatibilizer (D).
 14. The oxygen absorption resin composition of claim13, wherein the gas barrier resin (C) is contained in an amount of 70 to98.9 wt %, the thermoplastic resin (A) is contained in an amount of 29.9to 1 wt %, and the compatibilizer (D) is contained in an amount of 29 to0.1 wt %, when the total weight of the thermoplastic resin (A), the gasbarrier resin (C) and the compatibilizer (D) is determined to be 100 wt%.
 15. The oxygen absorption resin composition of any one of claims 9 to14, wherein particles of the thermoplastic resin (A) are dispersed in amatrix of the gas barrier resin (C).
 16. A molded product comprising theoxygen absorption resin composition of any one of claims 1 to
 15. 17. Amultilayered structure comprising a layer made of the oxygen absorptionresin composition of any one of claims 1 to
 15. 18. A multilayeredcontainer comprising a layer made of the oxygen absorption resincomposition of any one of claims 1 to
 15. 19. A multilayered containermade of a multilayered film having a total layer thickness of 300 μm orless, wherein the multilayered film comprises a layer made of the oxygenabsorption resin composition of any one of claims 1 to
 15. 20. Amultilayered container comprising a layer made of the oxygen absorptionresin composition of any one of claims 1 to 15 and a thermoplasticpolyester layer.
 21. A cap having a cap body that is provided with agasket made of the oxygen absorption resin composition of any one ofclaims 1 to 15.